THE 

CHEMICAL 


BLAIR 


S2S  Broadway 


REESE   LIBRARY 


UNIVERSITY    OF    CALI1         :NIA. 


> 


c 


THE 


CHEMICAL  ANALYSIS  OF  IRON 


A  COMPLETE  ACCOUNT  OF  ALL  THE  BEST 
KNOWN  METHODS 


FOR    THE 


Analysis  of  Iron,  Steel,  Pig-Iron,  Iron  Ore, 

Limestone,  Slag,  Clay,  Sand,  Coal,  Coke, 

and  Furnace  and  Producer  Gases. 


BY 

ANDREW   ALEXANDER   BLAIR, 

Graduate  United  States  Naval  Academy,  1866;  Chief  Chemist  United  States  Board  appointed  to 

Test  Iron,  Steel,  and  other  Metals,  1875;  Chief  Chemist  United  States 

Geological  Survey  and  Tenth  Census,  1880. 


PHILADELPHIA: 

J.    B.    LIPPINCOTT    COMPANY. 
1888. 


Copyright,  1888,  by  ANDREW  ALEXANDER  BLAIR. 


.vg^^r^3^. 

.||||>T^E.CTVFE§.A:PRihTER^|l|. 


TO    MY    WIFE, 

WITHOUT   WHOSE   ASSISTANCE   IT   WOULD    NEVER   HAVE 
BEEN   WRITTEN, 

THIS     VOIvUME 

IS    DEDICATED. 


PREFACE. 


THE  various  methods  for  the  analysis  of  iron  and  steel,  as  well 
as  the  descriptions  of  special  apparatus  to  facilitate  the  perform- 
ance of  the  analytical  work,  are  so  widely  distributed  through 
transactions  of  societies,  journals,  reviews,  periodicals,  and  works 
on  general  analytical  chemistry,  that  only  the  possessor  of  a 
chemical  library  can  command  the  literature  of  the  subject.  It 
is  my  object  in  the  following  pages  to  bring  within  the  compass 
of  a  single  volume,  as  nearly  as  possible,  all  the  methods  of  real 
value  to  the  iron  analyst,  and  in  doing  this  to  give  the  credit  of 
originality  for  the  different  methods  and  improvements  to  the 
proper  persons.  In  many  cases  this  has  been  very  difficult,  and 
I  shall  be  glad  to  have  any  mistake  that  I  have  made  brought  to 
my  attention. 

This  work  presupposes  some  knowledge  of  general  and 
analytical  chemistry,  and  some  practical  experience  in  laboratory 
work  and  manipulation,  as  it  is  intended  to  be  a  guide  for  the 
student  of  iron  chemistry  only.  For  such  persons  the  details 
of  the  descriptions  of  the  methods  will,  I  hope,  often  prove 
of  great  assistance.  With  very  few  exceptions,  these  descrip- 
tions are  the  results  of  my  own  experience  in  the  use  of  the 
methods,  and  the  details  are  those  that  seemed  to  me  to  be 
of  importance  in  their  practical  performance.  Many  of  the 
special  forms  of  apparatus  are  of  my  own  contrivance ;  they  have 
proved  extremely  useful  to  me,  and  I  hope  may  facilitate  in  some 
cases  the  work  of  iron  chemists,  to  whom  often  very  little  is  given 
and  of  whom  very  much  is  required. 


CONTENTS. 


PAGE 

APPARATUS 9 

APPARATUS  FOR  THE  PREPARATION  OF  THE  SAMPLES 9 

GENERAL  LABORATORY  APPARATUS 13 

REAGENTS .    31 

ACIDS  AND  HALOGENS,  32.     GASES,  36.     ALKALIES  AND  ALKALINE  SALTS,  37.     SALTS 
OF  THE  ALKALINE  EARTHS,  44.     METALS  AND  METALLIC  SALTS,  46.     REAGENTS 
FOR  DETERMINING  PHOSPHORUS,  51. 
METHODS   FOR   THE   ANALYSIS   OF   PIG-IRON,   BAR-IRON,  AND   STEEL   .    .    53 

DETERMINATION  OF  SULPHUR.  By  evolution  as  H2S.  Absorption  by  alkaline  solution 
of  nitrate  of  lead,  53-  -By  ammoniacal  solution  of  nitrate  of  silver,  55.  Absorption 
and  oxidation  by  bromine  and  HCl,  56.  Absorption  and  oxidation  by  peroxide  of 
hydrogen,  57-  Absorption  and  oxidation  by  permanganate  of  potassium,  57.  By 
oxidation  and  solution,  57.  Special  precautions  in  the  determination  of  S  in  pig- 
irons,  59.  RAPID  METHOD.  Volumetric  determination  by  iodine,  60. 

DETERMINATION  OF  SILICON,  63.  By  solution  in  HNO3  and  HC1,  63.  By  solution  in 
HNO3  and  H2SO4,  64.  By  volatilization  in  a  current  of  chlorine  gas,  65.  RAPID 
METHOD,  68. 

DETERMINATION  OF  SLAG  AND  OXIDES,  70.  By  solution  in  iodine,  70.  By  volatilization 
in  a  current  of  chlorine  gas,  71. 

DETERMINATION  OF  PHOSPHORUS,  72.  The  acetate  method,  72.  When  titanium  is 
present,  77.  The  molybdate  method,  80.  The  combination  method,  84.  When 
titanitim  is  present,  85.  RAPID  METHOD,  85. 

DETERMINATION  OF  MANGANESE,  90.  The  acetate  method,  90.  General  remarks  on  the 
acetate  method,  95.  The  HNO3  and  KC1O3  method  (Ford's),  96.  Steel  containing 
much  silicon,  97.  Pig-iron,  98.  Spiegel  and  f err o-manganese,  98.  RAPID  METHODS, 
98.  Volumetric  methods.  Volhard's  method,  98.  Williams's  method,  100.  Patti- 
soti's  method  (for  Spiegel  and  ferro-manganese],  103.  The  color  method  (for  steel), 
104. 

DETERMINATION  OF  CARBON,  106.  TOTAL  CARBON,  107.  Direct  combustion  in  a  cur- 
rent of  oxygen,  108.  Combustion  with  PbCrO4  and  KC1O3,  109.  Combustion  with 
CuO  in  a  current  of  oxygen,  112.  Solution  and  oxidation  of  the  borings  by  CrO3 
and  H2SO4,  113.  Volatilization  of  the  iron  in  a  current  of  Cl,  and  subsequent  com- 
bustion of  the  residue,  115.  Volatilization  of  the  iron  in  a  current  of  HC1  gas,  and 
subsequent  combustion  of  the  residue,  121.  Solution  in  NH4C1,  CuCl2,  filtration,  and 
weighing  or  combustion  of  the  residue,  121.  Solution  in  CuCl2  and  NaCl,  filtration, 
and  combustion  of  the  residue,  132.  Solution  in  CuCl2,  and  combustion  of  the  resi- 
due, 132.  Solution  in  I  or  Br,  and  combustion  with  PbCrO4,  or  weighing,  of  the  resi- 
due, 132.  Solution  by  fused  AgCl,  and  combustion  of  the  residue,  133.  Solution  of 
the  iron  in  CuSO4,  filtration,  and  combustion  of  the  residue  in  a  current  of  oxygen, 

7 


g  CONTENTS. 

PAGE 

134.  Solution  of  the  iron  in  CuSO4,  and  oxidation  of  the  residue  by  CrO3  -f-  H2SO4, 

135.  Solution  of  the  iron  in  CuSO4,  filtration,  and  combustion  of  the  residue,  mixed 
with  CuO  in  vacuo  under  the  Sprengel  pump,  the  volume  of  CO2  being  measured, 
135.     Solution  in  dilute  HC1  by  the  aid  of  an  electric  current,  and  combustion  of  the 
residue,  138.     Oxidation  of  the  iron  by  atmospheric  air  and  moisture,  solution  of  the 
ferric  oxide  in  HC1,  filtration,  and  combustion  of  the  residue,  139. 

DETERMINATION  OF  GRAPHITIC  CARBON 140 

DETERMINATION  OF  COMBINED  CARBON,   141.     Indirect  method,   141.     Direct  method 

(color  method),  141. 
DETERMINATION  OF  TITANIUM,  151.     By  precipitation,  151.     By  volatilization,  153. 

DETERMINATION  OF  COPPER 154 

DETERMINATION  OF  NICKEL  AND  COBALT 157 

DETERMINATION  OF  CHROMIUM  AND  ALUMINIUM,  159.     Volumetric  method  for  chro- 
mium, 163. 
DETERMINATION  OF  ARSENIC,  164.    By  precipitation  with  H2S,  164.    By  distillation,  165. 

DETERMINATION  OF  ANTIMONY 166 

DETERMINATION  OF  TIN 167 

DETERMINATION  OF  TUNGSTEN 168 

DETERMINATION  OF  VANADIUM 169 

METHODS   FOR   THE   ANALYSIS   OF   IRON   ORES 172 

Remarks  on  sampling,  172.  Determination  of  hygroscopic  water,  173.  Determination 
of  total  iron,  174.  Methods  for  standardizing  the  solutions,  179.  Determination  of 
FeO,  186.  Of  8,190.  OfP2O5,  192.  Of  TiO2,  194.  Of  Mn,  196.  Of  SiO2,  A12O3, 
CaO,  MgO,  MnO,  and  BaO,  199.  Of  SiO2,  208.  Separation  of  A12O3  and  Fe2O3,  209. 
Determination  of  NiO,  CoO,  ZnO,  and  MnO,  212.  Of  CuS,  PbS,  As2O3,  and  Sb2O4, 
214.  Of  the  alkalies,  216.  Of  CO2,  218.  Of  combined  water  and  carbon  in  car- 
bonaceous matter,  220.  Of  Cr2Os,  223.  Of  WO3,  225.  Of  V2O5,  225.  Of  sp.  gr., 
226. 

METHODS    FOR   THE   ANALYSIS   OF   LIMESTONE 228 

METHODS   FOR   THE   ANALYSIS   OF   CLAY 232 

METHODS   FOR   THE   ANALYSIS   OF   SLAGS 237 

METHODS   FOR   THE   ANALYSIS   OF   FIRE-SANDS 242 

METHODS   FOR   THE   ANALYSIS   OF   COAL   AND   COKE 243 

Proximate  analysis,  243.  Analysis  of  the  ash,  244.  Determination  of  sulphur,  245. 
Determination  of  phosphoric  acid,  247. 

METHODS   FOR  THE   ANALYSIS   OF  GASES 249 

Collecting  samples,  249.  Preparation  of  the  reagents,  252.  Analysis  of  the  samples,  254. 
Determination  of  CO2,  256.  Of  6,  257.  Of  CO,  257.  Of  H,  257.  Of  CH4,  259. 
Example  of  calculation,  263. 

TABLES 264 

Table  I.  Atomic  weights  of  the  elements,  264.     Table  II.  Table  of  factors,  265.     Table 
III.  Percentages  of  P  and  P2O5  for  each  m.g.  of  Mg2P2O7,  267.     Table  IV.  Tension 
of  aqueous  vapor,  268.     Table  V.  Table  for  reducing  volumes  of  gases  to  the  normal 
state,  269. 
INDEX    .  v  v 275 


THE  CHEMICAL  ANALYSIS  OF  IRON 


A  P  PA  R  AT  U  S. 

THE  speed  and  facility  with  which  results  may  be  obtained,  and  often 
the  accuracy  of  these  results,  are  dependent  upon  various  mechanical 
appliances  as  well  as  upon  the  skill  of  the  analyst.  These  appliances  will 
be  considered  under  separate  heads. 

APPARATUS  FOR  THE  PREPARATION  OF  THE  SAMPLES. 

For  crushing  iron  ores,  a  mortar  and  pestle,  such  as  are  ordinarily 
used,  have  caused  much  trouble.  In  breaking  up  hard  ores  the  wear, 
especially  on  the  pestle,  is  considerable,  and  the  particles  of  cast  iron 
may  cause  the  sample  to  yield  too  high  a  result  .in  the  assay  for  metallic 
iron.  Of  course  in  non-magnetic  ores  these  particles  may  be  removed  with 
a  magnet,  but  in  the  case  of  magnetic  or  partly  magnetic  ores  this 
cannot  be  done,  and  a  hardened  steel  mortar  and  pestle  should  be  used. 
The  sample  should  be  broken  to  about  pea  size,  well  mixed,  and  quar- 
tered, this  quarter  broken  still  finer,  and  mixed  and  quartered  in  the 
same  way  until  the  resulting  portion  is  small  enough  to  be  bottled.  The 
final  grinding  can  be  best  made  on  a  chilled-iron  plate  with  a  hardened 
steel  muller.  Except  with  unusually  refractory  ores,  further  grinding  is 
unnecessary,  but  with  such  ores  the  final  grinding  must  be  in  an  agate 
mortar.  In  large  laboratories  and  where  many  ores  are  analyzed,  arrange- 
ments such  as  are  shown  in  the  accompanying  sketches  will  prove  very 

2  9 


10 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


useful.  Fig.  I  shows  a  steel  mortar,  the  pestle  worked  by  power,  and 
a  chilled  plate  and  muller.  A  is  the  mortar ;  B,  a  wooden  stem  in  which 
the  pestle  fits.  The  cams  H  fit  on  the  shaft  and  raise  the  pestle  by 
means  of  the  tappets  a,  which  are  faced  with  raw  hide.  An  iron  hoop 
shrunk  on  the  mortar  has  a  ring,  in  [which  is  fastened  the  lower  block 
of  the  pulley  D  ;  the  upper  block  is  attached  to  a  traveller,  E.  When  in 
use  the  mortar  is  covered  with  a  leather  cap,  which  prevents  the  pieces 
of  ore  from  flying  out  of  the  mortar.  To  transfer  the  powdered  ore  to 

FIG.  i. 


the  chilled  plate  F,  remove  the  leather  cap,  raise  the  pestle  clear  of  the 
mortar,  and  fasten  it  up  by  a  hook  from  the  framework  to  the  tappet  a. 
Raise  the  mortar  by  pulling  the  fall  from  the  upper  block  and  fastening 
the  hook  in  its  end  into  a  ring  at  the  lower  block.  By  means  of  the 
traveller,  run  the  mortar  over  the  plate  and  turn  the  ore  out.  After 
quartering  the  sample  down,  finish  the  grinding  on  the  chilled  plate  with 
the  muller  C.  The  sheet-iron  troughs  G  serve  to  catch  any  ore  that 
falls  from  the  plate.  Fig.  2  shows  an  arrangement  for  facilitating  the 
final  grinding  in  the  agate  mortar,  in  which  the  pestle  is  rotated  by  a 


APPARA  TVS. 


II 


FIG.  2. 

CEILING  LINE 


Stow  flexible  shaft.  In  some  laboratories  a  small  Blake  crusher  is  used 
for  grinding  the  ore,  but  it  is  more  liable  to  get  out  of  order,  and  is 
not  so  easily  cleaned  as  the 
mortar  and  pestle. 

In  taking  samples  of  iron  or 
steel  a  perfectly  clean  dry  drill 
should  be  used,  and  the  utmost 
care  taken  to  prevent  grease, 
oil,  or  dirt  of  any  kind  from 
getting  in  the  sample.  With 
bar-iron  or  steel  the  scale 
on  the  outside  of  the  piece 
should  be  removed  as  carefully 
as  possible,  the  first  drillings 
from  each  hole  thrown  away, 
and  the  remainder  thoroughly 
mixed  and  placed  in  a  per- 
fectly clean  dry  bottle.  Fig. 
3  shows  a  convenient  form  of  drill-press  for  the  purpose.  A  half-inch 
Morse  twist-drill  is  the  best  for  general  use.  In  taking  samples  of  pig- 
iron,  the  loose  sand  should  be  carefully  removed  from  the  outside  of  the  pig 

FIG.  3. 


FLOOR  LINE 


and  a  piece  of  stout  paper  wrapped  around  it  to  prevent  the  sand  and 
slag  from  the  outside  getting  mixed  with  the  clean  drillings,  which  are 


12 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


FIG.  4. 


received    on   a   piece  of   glazed   paper   turned    up  at   the   edges   (Fig.   3). 

Drillings    from   pig-iron   can   be    best    mixed   by    rubbing   them    up    in    a 

small  porcelain  mortar. 
At  blast-furnaces,  to  save 
the  trouble  of  breaking 
pieces  from  the  pigs  the 
arrangement  shown  in 
Fig.  4  is  very  convenient, 
as  half  a  pig  can  be 
placed  in  the  press.  The 
framework  is  securely 

bolted  to  the  table  on  which  the  press  stands,  and  the  pig  is  secured  by 

means  of  the  iron  clamps.     By  removing  the  pieces  of  wood  under  the 

pig  it  is   lowered   so   that  two   or  three   holes   can  be  bored   in    different 

parts  of  the  face  of  the  pig  to  get  an  average.     By  taking  one  pig  from 

the  first  bed,  one  from  the  last,  and  one  from  an  intermediate  bed,  a  good 

average  of  each    cast  may  be   obtained.     When    the   ore  varies,  or  when 

mixtures  of  different  ores  are  used,  these   precautions  are  very  necessary 

to  get  a  sample  that  will  really  represent  an  average  of  the  cast. 
Drillings  from   large   ingots   must 

be  taken    by   means    of  an    ordinary 

brace. 

In  taking  samples  of  spiegel  or  of 

white-iron,  small  clean  pieces  from  a 

number  of  pigs  should  be  taken   and 

powdered  in  a  hardened  steel  mortar. 

The  mortar  shown  in  the  sketch  (Fig. 

5)  is   forged  from   high   carbon   steel, 

hardened,  and  the  temper  drawn  from 

the  outside.     This  makes  the  mortar 

both  hard  and  tough.     The  sheet-iron 

cover  prevents  the  pieces  from  flying. 

The  face  of  the  pestle  is  very  hard,  and  the  handle  comparatively  soft,  so 

that  it  will  not  break  when  struck  by  the  hammer. 


FIG.  5. 


APPARATUS.  j^ 

In  taking  samples  for  analysis,  when  the  method  used  requires  the 
sample  to  be  in  a  fine  state  of  subdivision,  the  very  fine  part  of  the  sample 
should  never  be  separated  from  the  coarser  particles  by  a  sieve  or  screen, 
but  the  sample  should  be  mixed  thoroughly,  and  a  portion,  fine  and  coarse 
together,  'taken  and  powdered,  so  that  all  may  pass  through  the  sieve. 


GENERAL  LABORATORY  APPARATUS. 

Sand-Bath  and  Air-Bath. 

FIG.  6. 


Fig.  6  shows  a  very  convenient  form  of  sand-bath,  and  Fig.  7  an  air- 
bath.     This  air-bath  is  made  from  an  ordinary  cast-iron  sink,  which  is  sup- 


14  THE    CHEMICAL   ANALYSIS   OF  IRON. 

ported  on  fire-bricks.  The  top  is  of  asbestos  board,  with  a  piece  of  sheet- 
iron  underneath  to  strengthen  it.  The  holes  are  large  enough  to  take  the 
largest-sized  beakers,  while  the  smaller  beakers  are  supported  by  asbestos 
rings.  An  ordinary  gas-regulator  or  governor,  which  supplies  the  gas  at  a 


FIG.  7. 


constant  pressure,  keeps  the  temperature  sufficiently  uniform.  Evaporations 
may  thus  be  effected  with  great  saving  of  time  and  with  little  danger  of  loss 
by  spirting.  The  products  of  combustion  of  the  gas  are  carried  off  by  a 
separate  flue,  and  the  H2SO4  formed  does  not  come  in  contact  with  the 
solutions  in  the  baths. 


APPARATUS. 


The  name  sand-bath  is  rather  a  misnomer,  for  it  is  generally  used  with- 
out sand,  the  surface  of  the  iron  being  kept  clean  and  free  from  rust  by  an 
occasional  coat  of  stove-polish.  Evaporations  on  the  sand-bath  may  be 
hastened  by  standing  the  beaker  containing  the  solution  inside  another 
beaker  with  the  bottom  cut  off.  Beakers  may  be  readily  cut  in  this  way  by 
starting  a  crack  and  leading  it  around  with  a  red-hot  iron  or  glass  rod.  For 
evaporating  solutions  in  capsules  or  dishes  a  beaker  cut  off  in  this  way  and 
placed  on  a  tripod  covered  with  wire  gauze,  as  shown  in  Fig.  8,  may  be  used 


FIG.  9. 


with  great  advantage.  The  capsule  is  supported  on  an  asbestos  ring,  A,  the 
bottom  being  about  J^  inch  (12  mm.)  from  the  wire  gauze.  A  piece  of 
thin  asbestos  board,  B,  about  ^  inch  (18  mm.)  in  diameter,  rests  on  the 
gauze  and  covers  the  point  of  the  flame  of  the  Bunsen  burner,  and,  by 
throwing  the  heat  more  on  the  sides  of  the  capsule,  tends  to  prevent  spirting 
when  the  solution  in  the  capsule  gets  thick  and  pasty. 


Hoods  for  Acid  Fumes. 

Hoods  provided  with  flues  for  carrying  off  the  acid  vapors  are  very 
necessary,  and  a  good  draft  may  always  be  insured  by  carrying  a  wooden 
flue  of  the  proper  size  through  the  roof  and  to  a  sufficient  distance  above  it, 
covering  it  with  a  cap  of  the  construction  shown  in  Fig.  9. 


i6 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Igniting-  Precipitates. 

For  ignitions,  a  Bunsen  burner  with  a  ring  to  regulate  the  supply  of  air, 
provided  with  an  ordinary  glass  chimney,  as  shown  in  Fig.  10,  is  most  con- 
venient. By  shutting  off  the  air  entirely  a  very  low  heat  may  be  obtained, 
which  is  not  rendered  variable  by  air-currents,  and  the  heat  of  the  full  flame 
of  the  burner  is  increased  by  the  greater  draft  caused  by  the  chimney  and 
the  perfect  steadiness  of  the  flame.  By  using  a  small  platinum  rod  or  wire 
to  support  the  cover  of  the  crucible,  as  shown  in  Fig.  10,  a  gentle  current  is 
induced  in  the  crucible,  which,  while  it  greatly  facilitates  burning  off  carbon, 
is  not  sufficiently  strong  to  cause  loss  by  carrying  off  even  the  lightest  ash. 


FIG.  10. 


FIG.  ii. 


FIG.  12. 


The  crucible  may  also  be  inclined  on  its  side,  as  in  Fig.  1 1 ,  the  heat  in  this 
case  being  applied  near  the  top  of  the  crucible.  Fig.  12  shows  an  easy 
method  of  fitting  a  chimney  to  a  Bunsen  burner  by  means  of  a  cork  and  an 
ordinary  Argand  chimney-holder.  When  a  higher  temperature  than  that 
obtainable  by  a  Bunsen  burner  is  required,  a  blast-lamp,  worked  by  a  foot- 
bellows,  by  a  water-blast,  or  by  a  small  blower,  is  used. 


APPARATUS. 


Tripods. 

The  most  convenient  arrangement  for  heating  liquids  in  beakers,  flasks, 
etc.,  is  the  iron  tripod  (Fig.  1  3).  It  consists  of  a  cast-iron  ring,  with  three 
legs  of  heavy  iron  wire  %  mc^  (6  mm.)  in  diam- 
eter.  The  ring  is  covered  with  brass  wire  gauze, 
40  meshes  to  the  inch,  which  can  be  replaced 
when  it  is  burned  out,  but  which  lasts  a  long 
time.  The  vertical  height  of  the  tripod  is  about 
7^  inches  (191  mm.).  A  very  convenient  form 
of  burner  is  the  Finkner  ratchet-burner,  as  the 
flame  can  be  raised  or  lowered  by  means  of  the 
ratchet  on  the  burner,  thus  avoiding  the  neces- 
sity of  reaching  back  over  the  table  to  the  gas- 
cock.  As  the  air  and  gas  are  both  turned  off  at  once,  there  is  less  danger 
of  the  flame  blowing  out  when  it  is  turned  very  low. 


Filter-Pumps. 

The  use  of  filter-pumps  for  Bunsen's  method  of  rapid  filtration  is  now 
very  general,  and  greatly  facilitates  many  operations.  The  kind  of  pump  is 
usually  determined  by  the  water-supply.  With  a  good  pressure  of  water, 
the  most  convenient  form  of  pump  is  the  injector.  Fig.  14  shows  the  Rich- 
ards' injector  united  with  a  blast-cylinder,  by  the  use  of  which  a  good  air- 
pressure  for  use  with  the  blast-lamp  may  be  obtained.  When  the  pump 
is  used  for  filtering  strong  solutions  of  HNO3  a  glass  injector  may  be  used, 
and  the  water  allowed  to  flow  at  once  into  the  sink  or  waste-pipe.  When 
the  pressure  of  water  is  not  great  enough  for  an  injector  the  Bunsen  pump 
may  be  used,  the  vacuum  obtained  of  course  depending  on  the  amount  of 
fall.  A  tank  with  a  ball-cock  attachment  makes  this  form  of  pump  most 
convenient. 

An  ordinary  air-pump  may  also  be  used  for  many  purposes,  but  of 
course  is  unsuitable  for  filtering  corrosive  liquids,  such  as  HNO3,  unless  a 
wash-bottle  containing  a  caustic  alkali  is  interposed  between  the  flask  and 


i8 


THE    CHEMICAL  ANALYSIS   OF  IRON. 


the  air-pump.     The  apparatus  shown  in  Fig.   1 5  will  give  a  very  good  idea 
of  an  arrangement  which   is  very  convenient  when  a  water-supply  is  not 

FIG.  14. 


available.     The  jug,  which  may  be  of  three  or  five  gallons  capacity,  serves 
as  a  reservoir.     It  connects  directly  with  the  air-pump. 

Bunsen's  Method  of  Rapid  Filtration. 

This  method  is  too  widely  known  to  make  a  detailed  description  neces- 
sary, but  some  hints  in  regard  to  the  details  may  be  useful.  In  the  first 
place,  it  is  very  difficult  to  get  good  60°  funnels,  so  that  the  little  perforated 
cones  of  platinum  to  support  the  point  of  the  filter,  which  are  sold  by  chem- 
ical dealers,  rarely  fit  the  funnel,  and  when  they  do  not  fit,  the  filters  are  apt 


APPARATUS. 


to  tear.     The  small  funnel  of  platinum-foil,  as  recommended  by  Bunsen,  can 
be  made  to  fit  the  funnel  better,  but  the  edges  sometimes  cut  the  filter.     A 

FIG.  15. 


small  funnel  of  parchment  pricked  full  of  pin-holes,  and  of  the  size  and 
shape  of  the  platinum-foil  funnel,  works  very  well.     It  FlG  l6 

is  a  mistake  to  use  too  great  a  pressure,  especially  at 
first,  and  the  filter  should  be  kept  full.  The  filtering 
flask  should  always  be  connected,  not  with  the  vacuum- 
pipe  directly,  but  with  another  flask  fitted  with  a  little 
Bunsen  valve,  which  allows  the  air  to  pass  into  the 
vacuum-pipe,  but,  in  case  of  a  sudden  stoppage  in  the 
pump,  prevents  the  back  pressure  from  entering  the  filter- 
ing-flask and  blowing  out  the  contents  of  the  funnel. 

Fig.  1 6  shows  an  arrangement  for  filtering  into  a 
beaker  instead  of  into  a  flask.  It  is  necessary  to  have  a 
glass  cover  over  the  beaker,  as  shown  in  the  sketch,  on  account  of  the  ten- 
dency the  solution  has  to  spatter,  particles  of  the  solution  being  carried  out 
of  the  beaker  in  the  current  of  air  flowing  into  the  vacuum-pipe. 


2O 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Gooch's  Method  of  Rapid  Filtration. 

The  pierced  crucible  and  cone,  with  asbestos  felt,  devised  by  Gooch,* 
are  almost  indispensable  to  the  iron  analyst  for  the  proper  and  rapid 
execution  of  many  operations,  as  will  be  seen  by  the  frequent  references  to 
them  in  the  descriptions  of  the  methods  given  farther  on.  Fig.  17  shows 
the  crucible  and  cap,  and  Fig.  18  the  cone.  The  asbestos,  which  should  be 
of  a  soft,  silky,  flexible  fibre,  is  scraped  longitudinally  (not  cut)  to  a  fine,  soft 
down,  and  purified  by  boiling  in  strong  HC1,  and  washed  thoroughly  on  the 


FIG.  17. 


FIG.  18. 


FIG.  19. 


cone.  It  may  be  dried  and  kept  in  a  bottle.  The  perforated  crucible  is 
placed  in  one  end  of  a  piece  of  soft  rubber  tubing,  the  other  end  of  which  is 
stretched  over  the  top  of  a  funnel,  as  shown  in  Figs.  17  and  19.  The  neck 
of  the  funnel  passes  through  the  stopper  of  a  vacuum-flask.  To  prepare 
the  felt,  pour  a  little  of  the  prepared  asbestos  suspended  in  water  into  the 
crucible  and  attach  the  pump.  The  asbestos  at  once  assumes  the  condition 
of  a  firm,  compact  layer,  which  is  washed  with  ease  under  the  pressure  of 
the  pump.  After  washing  the  felt,  suck  it  dry  on  the  pump,  remove  the 
crucible,  detach  any  little  pieces  of  fibre  that  may  be  on  the  outside  of  the 
bottom  of  the  crucible,  slip  on  the  little  cap,  dry,  ignite,  and  weigh. 
Remove  the  cap,  place  the  crucible  in  the  rubber  holder,  start  the  pump 
and  pour  the  liquid  and  precipitate  to  be  filtered  into  the  crucible,  wash, 
dry,  ignite,  if  required,  cool,  and  weigh  as  before.  The  cone  is  fitted  to  a 
funnel  by  means  of  a  rubber  band  stretched  over  the  top  of  the  funnel. 


Proceedings  Am.  Acad.  Arts  and  Sciences,  1878,  p.  342;  Chem.  News,  xxxvii.  181. 


APPARATUS.  21 

The  pressure  of  the  pump  pulls  the  cone  down  so  that  the  overlapping  part 
of  the  band  forms  a  tight  joint  between  the  cone  and  the  upper  part  of  the 
funnel  (Fig.  20).  The  felt  is  prepared  in  the  same  manner  as  in  the  crucible. 
Fill  the  cone  with  the  asbestos  suspended  in  water,  FIG 

start  the  pump,  press  down  the  cone  into  the  funnel, 
and,  if  necessary,  pour  in  more  of  the  asbestos,  letting 
it  run  all  around  from  the  upper  edge  of  the  cone  so 
as  to  fill  all  the  holes  and  make  a  firm,  cohesive  layer 
all  over  the  inside  of  the  perforated  portion  of  the 
cone.  Wash  it  well  with  water  and  suck  it  dry.  It 
will  then  be  ready  for  use.  The  cone  is  not  intended 
for  use  when  the  precipitate  is  to  be  weighed,  but,  as  it 
presents  a  very  large  filtering  surface,  it  is  most  useful  for  such  precipitates 
as  MnO2  precipitated  by  Ford's  method,  etc.  In  this  case,  when  the  precipi- 
tate has  been  washed  and  sucked  dry,  by  removing  the  cone  from  the  funnel 
and  carefully  separating  the  felt  from  the  sides  of  the  cone  with  a  little  piece 
of  flattened  platinum  wire,  it  may  be  removed  from  the  cone  with  the  pre- 
cipitate enclosed  in  it,  and  the  whole  mass  transferred  to  a  beaker  or  flask 
for  resolution.  The  cones  may  be  of  various  sizes;  for  ordinary  use,  a  cone 
\y±  inches  (45  mm.)  in  diameter  is  very  convenient.  They  may  also  be 
used  with  a  paper  filter.  In  both  the  crucibles  and  cones  the  holes  should 
be  very  small,  and  drilled  (not  punched)  as  closely  together  as  possible. 

Counterpoised  Filters. 

The  Gooch  crucible  and  felt  are  most  useful  for  weighing  precipitates 
which  are  to  be  dried  and  not  ignited,  as  in  the  direct  weighing  of  the 
phospho-molybdate  of  ammonium.  When  they  are  not  available,  however, 
recourse  must  be  had  to  counterpoised  filters.  The  best  method  for  pre- 
paring and  using  them  is  as  follows :  Take  two  washed  filters  of  the 
same  size  and  about  the  same  thickness,  fold  them  as  if  about  to  fit 
them  in  funnels,  and,  by  cutting  from  the  upper  edge  of  the  heavier  of 
the  two  with  a  pair  of  scissors,  make  them  nearly  balance.  Place  them 
between  a  pair  of  watch-glasses,  as  shown  in  Fig.  21,  dry  them  at  100° 
C,  and  allow  them  to  cool  in  a  desiccator.  Place  one  in  each  pan  of 


22  THE   CHEMICAL  ANALYSIS   OF  IRON. 

the  balance,  and,   handling   them  with  a  pair  of  forceps,  clip  them   until 
FlG  2I  they  balance  exactly.     Place  each  filter  in  a  funnel, 

filter  the  precipitate  on  one  of  them,  pass  the  clear 
filtrate  (not  the  washings)  through  the  other,  and 
wash  them  both  in  the  same  manner.  Remove 
them  from  the  funnels,  turning  over  the  top  edges 
of  the  filter  containing  the  precipitate  to  prevent 
any  of  the  latter  from  falling  out,  place  them  in  a  watch-glass,  dry  them 
at  1 00°  C.  (or  at  the  required  temperature,  whatever  it  may  be),  cover 
them  with  the  other  watch-glass,  cool  in  a  desiccator,  place  them  on 
opposite  pans  of  the  balance,  and  the  weight  added  to  the  pan  contain- 
ing the  empty  filter,  to  make  them  balance,  is  the  weight  of  the  pre- 
cipitate. 

Filter-Paper. 

All  filter-paper  contains  more  or  less  inorganic  matter,  which  remains, 
after  burning  the  paper,  as  a  white  or  brownish  ash.  The  Swedish  paper 
with  the  water-mark  J.  H.  Munktell  leaves  the  smallest  amount  of  ash, 
and  this  ash  contains  from  35  to  65  per  cent,  silica,  besides  ferric  oxide, 
alumina,  lime,  and  magnesia  in  varying  proportions. 

Schleicher  &  Schull  prepare  some  very  pure  filters  by  washing  them 
with  HC1  and  HF1,  and  these  should  always  be  used  for  very  accurate 
work,  unless  the  analyst  prepares  ashless  papers  for  himself.  The  com- 
moner kinds  of  German  paper  contain  much  larger  amounts  of  inorganic 
matter  than  the  Swedish  paper,  and  it  usually  consists  principally  of 
carbonate  of  calcium,  but  sometimes  contains  appreciable  amounts  of 
phosphates. 

Filters  of  this  kind  should  always  be  washed  with  HC1  before  they 
are  used.  They  may  be  washed  by  fitting  them  in  a  funnel,  pouring  on 
hot  HC1  and  water  (i  part  acid  to  3  parts  water),  and,  washing  thoroughly 
with  hot  water.  They  may  also  be  washed  in  the  apparatus  shown 
in  Fig.  22.  It  consists  of  a  bottle  of  the  proper  size  with  the  bottom 
cut  off  with  a  hot  iron.  It  contains  a  disk  of  wood  cut  to  fit  the  shape 
of  the  bottle  and  perforated  with  a  number  of  gimlet-holes.  Fill  the  bottle 
half  full  of  cut  filters,  pour  on  a  mixture  of  HC1  and  water  (1-3),  allow 


APPARATUS. 


them  to  stand  about  half  an  hour,  and  wash  thoroughly  with  distilled  water. 
The  bottle  may  be  attached  to  the  vacuum-pump  and  washed  under 
pressure.  Dry  the  filters  at  a  temperature  below  100°  C.  For  prepar- 
ing ashless  filters  the  apparatus  shown  in  Fig.  23  is  used.  It  is  of  spun 
copper,  lined  with  platinum  throughout.  Over  the  vertical  tube  is  a 
perforated  platinum  disk  countersunk  to  the  level  of  the  bottom  of  the 


FIG.  22. 


FIG.  23. 


dish.  It  is  attached  to  the  pump,  and  the  filters  are  washed  first  with 
HC1  and  water  (1-3),  then  with  water  to  remove  the  lime,  then  with 
HF1  and  water  (1-3)  to  dissolve  the  silica,  and  finally  with  distilled 
water.  Swedish  filters  washed  in  this  way  are  practically  ashless,  the  ash 
from  five  filters,  each  3  inches  (75  mm.)  in  diameter,  weighing  less  than 
^  mg.  Filters  may  be  cut  out  by  tin  disks  of  the  proper  diameter ;  they 
may  be  bought  ready  cut,  or  they  can  be  cut  out  at  shops  where  they 
cut  circular  labels  at  very  small  cost.  The  best  way  is  to  buy  Swedish 
paper  and  a  good  tough  German  paper,  by  the  ream,  have  the  paper 
cut  into  filters  of  the  proper  sizes,  say  5^2  inches  (140  mm.),  4^  inches 
(108  mm.),  and  3  inches  (76  mm.)  in  diameter,  and  wash  the  Swedish 
with  HC1  and  HF1  and  the  German  with  HC1.  The  ashless  filters  can 


THE   CHEMICAL   ANALYSIS  OF  IRON. 


be    used   for   final    filtrations   when   the   precipitate   is   to   be   ignited   and 
weighed,  and  the  German  for  all  other  work. 

Washing-Bottles. 

Figs.  24,  25,  and  26  represent  different  forms  of  washing-bottles. 
For  ordinary  use  that  represented  in  Fig.  24  is  the  best.  The  neck 
is  wrapped  with  thin  asbestos  board,  covered  with  a  piece  of  wash- 
leather  or  chamois,  which  is  sewed  to  keep  it  from  slipping.  This  is 
very  necessary  when  hot  water  is  used  in  it.  A  piece  of  soft  rubber 
tubing  at  A  is  more  pleasant  for  the  mouth  than  the  glass,  and  after 
compressing  the  air  in  the  flask  the  tube  can  be  grasped  with  the  teeth, 
thus  keeping  up  the  stream  of  water  for  some  time  without  effort.  It 


FIG.  24. 


FIG.  25. 


FIG.  26. 


also  prevents  the  lips  from  being  scalded  when  using  very  hot  water. 
Fig.  25  shows  a  movable  tip,  which  allows  the  stream  of  water  to  be 
directed  by  means  of  the  finger.  The  form  of  flask  shown  in  Fig.  25 
is  very  convenient  to  use  with  ammonia-water,  etc.  The  tube  a  is 
closed  with  the  index  finger,  while  the  Bunsen  valve  b  closing  as  soon 
as  the  air  is  compressed  in  the  flask  prevents  the  vapors  from  coming 
back  into  the  mouth,  and  the  stream  of  liquid  is  stopped  instantly  by 
removing  the  finger  from  a.  Fig.  26  shows  the  Berzelius  form,  which 
is  sometimes  very  useful.  The  air  is  compressed  by  blowing  into  the 
bottle  through  the  jet,  and  by  quickly  inverting  the  bottle  the  stream 


APPARATUS. 


of  liquid  is  forced  out  until  the  equilibrium  is  restored.  It  requires 
a  little  practice  to  use  this  form  of  bottle  easily,  but  when  the  art  is 
once  acquired  it  can  be  used  with  ammonia-water  as  well  as  pure  water, 
and  the  facility  with  which  it  can  be  moved  and  pointed  in  any  direction 
with  the  hand  makes  it  most  convenient  for  some  purposes. 

Removing-  Precipitates  from  Beakers. 

A  feather  trimmed  in  the  way  shown  in  Fig.  27  may  be  used  to 
remove  particles  of  adhering  precipitates  from  beakers,  evaporating-dishes, 
etc.  A  piece  of  soft  rubber  tubing  on  the  end  of  a  piece  of  glass  rod 
or  sealed  glass  tube  is  much  more  effective  and  convenient  in  most  cases. 


FIG.  27. 


FIG.  28. 


FIG.  29. 


It  is  made  by  taking  a  short  length  of  rubber  tubing,  placing  a  little 
pure  caoutchouc  dissolved  in  chloroform  in  one  end,  squeezing  the  sides 
together  between  two  pieces  of  board  (Fig.  29),  and  allowing  it  to  re- 
main for  at  least  twenty-four  hours.  It  may  then  be  trimmed  down  and 
placed  on  the  end  of  a  piece  of  glass  rod  or  on  the  end  of  a  piece  of 
glass  tubing  having  the  ends  fused  together  (Fig.  28).  This  little  instru- 
ment has  acquired  the  name  of  "  policeman." 

Measuring-Glasses. 

In  adding  reagents  to  a  sample  or  to  a  solution,  measured  amounts 
should  nearly  always  be  used,  and,  as  it  is  generally  well  under 
all  circumstances  to  avoid  adding  them  from  the  bottle  direct, 
little  beakers  of  the  form  shown  in  Fig.  30  are  very  useful. 
They  can  be  graduated  and  marked  by  covering  the  side  with 
a  thin  coating  of  paraffine,  measuring  in  water  from  a  burette, 
marking  the  levels  and  amounts  in  the  paraffine  with  a  sharp- 
pointed  instrument,  and  etching  them  in  the  glass  by  filling  the  marks 

3 


26  THE    CHEMICAL   ANALYSIS   OF  IRON. 

with  HF1.  After  standing  a  few  minutes  the  HF1  may  be  washed  off 
under  the  hydrant  and  the  paraffine  removed  with  hot  water.  As  the 
amounts  are  intended  to  be  only  approximate,  no  great  degree  of  care 
need  be  exercised  in  the  graduation. 

Caps  for  Reagent-Bottles. 

The  stoppers  and  lips  of  reagent-bottles  are  very  apt  to  become 
covered  with  chloride  of  ammonium,  dust,  etc.,  when  exposed  in  the 
laboratory,  and  especially  such  as  are  not  in  constant  use,  volumetric 
solutions,  stock-bottles,  etc.  It  is  well  to  keep  them  always  covered 
with  caps,  which  may  be  bought  from  the  dealers,  or  with  cracked 
beakers,  which  answer  the  purpose  nearly  as  well  in  most  cases. 

Rubber  Stoppers. 

Rubber  stoppers  are  now  generally  used  instead  of  cork.  Solid 
stoppers  should  always  be  purchased,  and  the  holes  cut  with  the  ordinary 
cork-borers.  This  is  readily  done  by  moistening  the  cork -borer  with 
water  or  alcohol.  A  little  practice  will  enable  any  one  to  do  this  with 

great  ease. 

Desiccators. 

Crucibles    should    always    be    cooled   before   weighing    in    desiccators. 
FlG  3I  The  form  shown  in  Fig.  31  is  most  convenient.     The 

desiccator  should  contain  fused  chloride  of  calcium- 
The  crucible  rests  on  a  small  triangle,  which  may 
be  made  of  copper  wire,  each  side  being  covered 
by  winding  a  thin  strip  of  platinum  foil  around  it 
to  prevent  the  crucible  from  coming  in  contact  with 
the  copper,  which  may  become  more  or  less  cor- 
roded. 

PLATINUM   APPARATUS. 

Crucibles. 

The  shape  of  the  crucible  is  of  considerable  importance  as  regards 
its  wearing  properties.  Fig.  32  shows  the  best  form  for  general  use. 


APPARATUS.  2J 

A  crucible  \y2  inches  (38  mm.)  high,  i^-  inches  (33^2  mm.)  wide  at 
the  top,  with  a  capacity  of  20  c.c.,  and  weighing  with  the  lid  about  25 
grammes,  is  well  adapted  for  weighing  the  usual  precipi-  JTIG  .2 

tates  found  in  the  course  of  iron  analysis.  For  fusions  a 
much  larger  crucible  is  necessary :  one  i-^f  inches  (46 
mm.)  high,  i-^f  inches  (46  mm.)  wide  on  top,  with  a  capa- 
city of  55  c.c.,  and  weighing  about  60  grammes,  will  be 
found  convenient  and  serviceable.  Pure  platinum  is  the 
best  metal  for  crucibles.  The  iridium  alloy,  at  one  time  so  popular,  has 
not  been  found  to  wear  well.  It  is  stiffer  than  the  pure  metal,  but  mucl 
more  liable  to  crack.  The  endurance  of  a  crucible  depends  very  much 
upon  the  treatment  it  receives.  The  salts  of  easily  reduced  metals  fusing 
at  a  low  temperature,  such  as  lead,  tin,  bismuth,  antimony,  etc.,  should 
never  be  ignited  in  platinum ;  besides  these,  the  phosphoric  acid  in  some 
phosphates  is  occasionally  partly  reduced,  rendering  the  platinum  very 
brittle.  A  platinum  crucible  should  never  be  bent  out  of  shape  when 
it  can  be  avoided,  and  a  wooden  plug  exactly  the  shape  of  the  crucible 
(Fig.  33)  is  very  useful  to  straighten  it  on  when  it  has  been  bent.  It 
should  always  be  carefully  cleaned  before  use :  the  precipitate  FlG 
last  ignited  should  be  dissolved  in  acid  if  possible,  and  the 
crucible  washed  out  with  water,  dried,  ignited,  and  cooled  in  a 
desiccator  before  weighing.  A  precipitate  of  Fe2O3  will 
sometimes  stain  a  crucible  very  badly;  this  stain  may  be 
removed  by  allowing  the  crucible  to  stand  with  cold  HC1 
for  twelve  hours,  and  then  warming  it  for  a  short  time.  V  /^ 

Stains  that  are  not  removed  by  HC1  may  be  removed  by 
fusing  KHSO4  in  the  crucible,  or  by  fusing  Na2CO3  in  it,  dissolving  in 
water,  and  then  treating  the  crucible  with  HC1.  Whenever  a  crucible 
begins  to  look  dull  and  tarnished  it  should  be  cleaned  inside  and  out 
with  very  fine  sea-sand  (not  sharp  sand)  by  moistening  the  finger,  dip- 
ping it  in  the  sand,  and  rubbing  the  crucible  with  it.  This  method  of 
cleaning  decreases  the  weight  of  the  crucible  very  slightly,  the  sea-sand 
burnishing  without  cutting  the  crucible.  It  is  very  convenient  to  have 
each  crucible  and  its  cover  marked  with  a  number,  as  shown  in  Fig.  32. 


28 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


FIG.  35. 


Dishes. 

Fig.  34  shows  a  very  convenient  form  of  dish  for  the  determination  of  Si 
in  pig-iron,  SiO2  in  iron  ores,  etc.     It  is  3^  inches  (83  mm.)  in  diameter 

and  2*^  inches  (57  mm.)  high. 
Fig.  35,  for  such  work  as  precipi- 
tation of  Fe2O3,  etc.  It  is  5  inches 
(127  mm.)  in  diameter  and  3^- 
inches  (84  mm.)  high.  The  wire 
which  is  fused  into  the  top  of  the 
dish  makes  it  much  stififer  than  it 
would  otherwise  be,  and  consequently  it  may  be  made  lighter  and  cheaper 
than  would  be  possible  without  the  wire.  The  wire  is  hammered  out  and 
helps  to  form  the  lip.  A  platinum  stirring-rod,  formed  from  a  piece  of 
seamless  tubing,  rounded  and  fused  together  at  the  ends,  is  useful  for 
many  purposes.  It  may  be  from  ^/2  to  7  inches  (140  to  179  mm.)  long, 
J^  inch  (6  mm.)  in  diameter,  weighing  from  7.5  to  n  grammes. 


Spatula. 

Fig.  36  shows  a  very  convenient  and  useful  form  of  spatula.     The  blade, 

FIG.  36.  which  is  made  of  the  platinum-iridium  alloy,  is  fused 

(  ->-  =3    into  a  tube  of  the  same  alloy  which  forms  the  handle. 

The  weight  of  the  spatula  shown  in  the  sketch  is   14  grammes,  length  6^ 

inches  (165   mm.). 

Triangles  and  Tripods. 

The  triangles  for  supporting  the  crucibles  during  the  ignition  are  shown 
in  Figs,  ii  and  12,  as  are  also  tripods  for  holding  the  lids,  etc.  These 
are  made  from  wire  about  ^  inch  (1.6  mm.)  diameter,  the  ends  are  fused, 
and  the  wire,  where  it  is  twisted,  has  the  parts  in  contact  fused  together 
almost  to  the  inside  of  the  triangle,  which  makes  it  much  stiffen  The 
triangles  should  be  attached  to  the  iron  rings  of  the  supports  with  a  few 
turns  of  fine  platinum  wire. 


APPARATUS.  29 

Crucible-Tongs. 

Fig.  37  shows  the  best  form  of  crucible-tongs.  The  part  from  a  to  b  is 
of  platinum,  the  straight  part  from  a  to  c  fitting  over  the  end  of  the  iron. 
The  surfaces  at  d  are  in  contact  when  the  tongs  are  closed,  and  with  this 
portion  the  lid  can  be  handled,  and  the  crucible  is  clasped  by  the  curved 
ends,  which  hold  it  firmly  without  any  danger  of  bending  the  crucible. 


FIG.  38. 


FIG.  37 


They  are  especially  useful  in  handling  a  crucible  containing  a  liquid  fusion. 
Another  form,  shown  in  Fig.  38,  are  generally  of  brass,  the  points  and  bend 
being  lined  with  platinum.  A  small  pair  of  forceps  (Fig.  39)  is  useful  for 
taking  the  crucible  from  the  desiccator  and  placing  it  on  the  balance,  the  lid 
of  the  crucible  being  slipped  a  little  to  one  side  to  allow  one  of  the  points 
of  the  forceps  to  go  inside  the  crucible. 


Balances. 

The  balance  is  one  of  the  most  important  things  in  the  equipment  of 
a  laboratory,  and  a  cheap  balance  is  nearly  always  a  very  poor  investment. 
The  quality  of  balances  has  improved  greatly  in  the  last  few  years,  and 
it  is  now  possible  to  get  a  most  admirable  instrument  of  this  kind  at  a 
comparatively  low  price.  Fig.  40  shows  a  balance  which  for  sensitiveness 
and  quickness  is  unsurpassed.  It  is  made  to  carry  up  to  200  grammes  in 
each  pan.  The  beam  is  of  aluminium,  as  are  also  the  pans.  The  stirrups 
are  of  nickel,  the  knife-edges  and  bearings  of  agate,  while  the  arrangement 
for  carrying  the  riders  (Fig.  41)  is  most  ingenious  and  effective.  It  is  of 
course  very  convenient  to  have  one  balance  for  weighing  crucibles,  etc.,  and 
another  for  weighing  samples  for  analysis.  The  balance  for  the  latter  pur- 
pose may  be  much  smaller  than  the  balance  for  the  former,  and  should  be 


THE   CHEMICAL   ANALYSIS   OF  IRON. 
FIG.  40. 


f3)          (T  o  | 

^                    x^/ 
© 

0 

FIG.  41. 


provided  with  a  small  aluminium  pan  with  a  spout  (Fig.  42),  to  facilitate  the 

transfer  of  samples  to  flasks, 
test-tubes,  etc.  This  pan 
should  have  a  counterpoise. 
A  pair  of  small  forceps, 
slightly  magnetized,  may  be 
used  to  advantage  in  getting 

FIG.  42. 


exact  weights  of  steel  drillings,  and  a  camel's-hair  brush  is  necessary  to 
detach  small  particles  of  ores,  etc.,  from  the  aluminium  pan  or  balanced 
watch-glasses. 


REAGENTS. 


REAGENTS. 

Distilled  Water. 

When  only  a  small  amount  of  distilled  water  is  needed,  a  tin-lined  cop- 
per still  and  condenser,  such  as  are  furnished  by  all  dealers,  may  be  used, 
but  where  there  is  a  supply  of  steam,  an  arrangement  like  that  shown  in 
Fig.  43  will  be  found  most  useful.  A  is  a  tin-lined  copper  cylinder,  with 
a  dome-shaped  top,  E,  fitted  to  A  by  the  joint  shown  in  the  sketch,  which 

FIG.  43. 


fUV7 


may  be  made  tight  by  paper  or  a  linen  rag.  Two  perforated  shelves,  a,  a, 
support  layers  of  clean  quartz-gravel  or  pieces  of  block-tin,  which  wash  the 
steam  and  prevent  dirt  from  being  carried  over  mechanically.  The  steam 
enters  at  B,  and  the  water  condensed  in  the  cylinder  A  passes  off  through 
the  pipe  C.  The  washed  steam  passes  up  through  the  block-tin  pipe  G,  and 
is  condensed  in  the  worm-tub  F.  A  glass  worm  should  never  be  used,  as 
the  water  condensed  in  it  dissolves  notable  amounts  of  glass. 


32  THE    CHEMICAL   ANALYSIS   OF  IRON. 

ACIDS   AND    HALOGENS. 

Hydrochloric  Acid.     HC1.     Sp.  gr.  1.2. 

Chemically  pure  hydrochloric  acid  is  readily  obtained.  It  should  be  free 
from  chlorine,  sulphuric  and  sulphurous  acid,  arsenic,  and  fixed  salts.  To 
test  for  sulphuric  and  sulphurous  acid,  evaporate  100  c.c.  to  dryness  with 
a  little  pure  nitrate  of  potassium,  redissolve  in  water  with  a  few  drops  of 
HC1,  filter,  if  necessary,  and  add  chloride  of  barium.  To  test  for  arsenic, 
put  into  a  clean  dry  test-tube  a  few  centigrammes  of  pure  stannous  chloride, 
pour  in  carefully  6  or  8  c.c.  HC1,  and  gradually  2  or  3  c.c.  pure  H2SO4, 
shaking  the  test-tube  gently.  If  the  HC1  is  free  from  arsenic  the  solution 
remains  clear  and  colorless,  but  if  arsenic  is  present  the  solution  becomes 
yellowish,  then  brownish,  and  finally  metallic  arsenic  is  deposited.  The 
test-tube  should  be  gently  warmed  if  no  reaction  occurs  at  first.  To  test  for 
chlorine,  pour  some  of  the  acid  into  a  solution  of  iodide  of  potassium  con- 
taining a  little  starch  solution.  A  blue  coloration  indicates  chlorine  or  ferric 
chloride.  To  test  for  metallic  salts,  neutralize  about  100  c.c.  of  the  acid 
with  ammonia  and  add  sulphide  of  ammonium.  To  test  for  salts  of  the 
alkalies,  evaporate  about  100  c.c.  of  the  acid  to  dryness,  and  test  any 
residue  which  may  remain. 

Nitric  Acid.     HNO3.     Sp.  gr.  1.41. 

Nitric  acid  should  be  free  from  nitrous  acid,  the  presence  of  which  may 
be  known  by  the  yellowish  color  it  produces.  It  may  be  freed  from  this 
gas  by  passing  a  current  of  air  through  the  acid  until  it  becomes  colorless. 
To  test  for  HC1  or  Cl,  dilute  largely  and  add  a  solution  of  nitrate  of  silver. 
To  test  for  fixed  salts,  evaporate  about  100  c.c.  to  dryness.  The  ordinary 
acid  diluted  with  an  equal  volume  of  water  gives  the  acid  of  1.2  sp.  gr. 
used  to  dissolve  steel  for  the  color  carbon  test.  It  should  be  carefully 
tested  for  chlorine  or  HC1. 

Sulphuric  Acid.     H^SO^     Sp.  gr.  1.84. 

Sulphuric  acid  should  be  colorless.  To  test  for  oxides  of  nitrogen, 
Warington*  suggests  placing  about  two  pounds  of  the  acid  in  a  bottle, 

*  Crookes's  Select  Methods,  2d  ed.,  p.  494. 


REAGENTS. 


33 


FIG.  44. 


which  it  half  fills,  and  shaking  violently.  The  air  washes  the  gases  out 
of  the  acid,  and  the  presence  of  the  oxides  of  nitrogen  may  be  detected  by 
placing  in  the  mouth  of  the  bottle  a  piece  of  filter-paper  saturated  with 
iodide  of  potassium  and  starch  solution,  which  is  colored  blue  when  any 
of  these  oxides  are  present.  To  test  for  lead,  supersaturate  some  of  the 
acid  with  ammonia  and  add  sulphide  of  ammonium. 

Hydrofluoric  Acid.     HP1. 

It  is  quite  impossible  to  purchase  pure  hydrofluoric  acid,  for  the  acid 
acts  on  the  substance  of  any  containing  vessels,  even  those  of  gutta-percha, 
in  which  the  so-called  pure  acid  is  usually  sold.  As  it  is  a  most  useful 
reagent  in  iron  analysis,  it  is  better  to  purify  it  in  the  laboratory  and  keep  it 
in  a  platinum  bottle.  The  crude  acid,  which  may  be  purchased  from  glass 
engravers  and  etchers,  is  distilled  from  a  platinum,  silver,  or  lead  still,  as 
shown  in  Fig.  44.  The  head  of  the  still  and  condensing-tube  is  of  plat- 
inum. The  condensing-tube 
runs  through  a  copper  box 
filled  with  ice,  and  a  plati- 
num bottle  receives  the  con- 
densed acid.  Where  the  tube 
comes  through  the  lower  part 
of  the  box  it  is  secured  by  a 
rubber  stopper,  and  a  small 
bit  of  paper  around  the  tube 
prevents  any  condensed  moist- 
ure on  the  outside  of  the  tube 
from  running  into  the  bottle.  Before  distilling  the  acid,  put  into  it  a  few 
crystals  of  permanganate  of  potassium  and  a  few  c.c.  of  H2SO4.  The  re- 
distilled acid  should  leave  no  residue  upon  evaporation. 

Acetic  Acid.     H,C2H3O2.     Sp.  gr.  1.O4. 

Acetic  acid  of  the  strength  given  above  is  the  best  for  use  in  iron  analy- 
sis. It  should  give  no  residue  on  evaporation,  and  no  precipitate  upon  neu- 
tralization with  ammonia  and  the  addition  of  sulphide  of  ammonium.  It 


34  THE    CHEMICAL   ANALYSIS   OF  IRON. 

should  be  free  from  phosphoric  acid.  To  test  it  for  phosphoric  acid,  evapo- 
rate 100  c.c.  nearly  to  dryness,  add  a  little  magnesium  mixture  and  a  large 
excess  of  ammonia,  cool  in  ice-water,  and  stir  vigorously.  When  phos- 
phoric acid  is  present,  a  precipitate  of  phosphate  of  ammonium  and  magne- 
sium will  be  obtained. 

Citric  Acid.     H3,C6H5O7,H2O. 

Citric  acid  is  easily  obtained  in  a  state  of  purity  in  the  form  of  crys- 
tals having  the  above  composition.  It  should  be  kept  in  the  solid  condi- 
tion, and  dissolved  as  needed.  It  is  soluble  in  ^  part  of  water  at  15°  C. 

Tartaric  Acid.     H2,C4H4O6. 

Tartaric  acid  is  also  easily  obtained  sufficiently  pure  for  use  in  iron 
analysis.  The  crystals,  having  the  composition  H2,QH4O6,  should  be  dis- 
solved only  as  needed.  The  only  impurity  is  a  small  amount  of  lime. 
It  is  soluble  in  ^  part  of  water  at  15°  C. 

Oxalic  Acid.     H2,C2O4. 

Oxalic  acid  crystallizes  from  its  aqueous  solution  as  H2,C2O4,2H2O, 
soluble  in  8.7  parts  of  water  at  15°  C.  It  loses  its  water  of  hydration  very 
easily  even  at  the  ordinary  temperature  in  dry  air,  and  very  quickly  at 

100°   C. 

Bromine.     Br. 

Bromine  is  easily  obtained  in  a  condition  sufficiently  pure  for  use  as 
a  reagent.  It  is  a  dark  brown,  extremely  corrosive  liquid,  of  sp.  gr.  2.97. 
It  is  soluble  in  about  30  parts  of  water  at  15°  C.  It  is  best  kept  in  a 
glass-stoppered  bottle  with  a  ground  cap.  As  the  aqueous  solution  is 
generally  used,  it  is  convenient  to  put  only  a  small  amount,  say  20  or  30 
c.c.,  in  the  bottle,  fill  the  bottle  nearly  full  of  cold  distilled  water,  shake 
it  up  well,  and  pour  off  the  saturated  solution  as  required.  There  usually 
remains  in  the  bottom  of  the  bottle  a  small  amount  of  impurity,  which 
is  insoluble  in  water. 

Iodine.     I. 

Iodine  is  a  metallic-looking  crystalline  solid,  of  sp.  gr.  4.95.  Resub- 
limed  iodine  is  not  sufficiently  pure  for  use,  and  must  be  redistilled  with 


REAGENTS.  ~* 

great  care,  unless  it  is  used  as  iodine  dissolved  in  iodide  of  iron,  and 
filtered.  To  distil  it,  place  about  y2  kilo,  in  a  large  glass  retort  of  about 
2  litres  capacity  connected  with  an  adapter  about  18  inches  (456  mm.)  long 
and  3  inches  (75  mm.)  in  diameter  at  the  largest  part.  The  heat  from 
a  Bunsen  burner  turned  quite  low  will  cause  the  violet  vapors  of  iodine 
to  pass  rapidly  into  the  adapter,  where  they  will  condense  without  any 
means  being  taken  to  cool  it.  By  gently  warming  the  outside  of  the 
adapter  after  the  distillation  has  been  finished,  the  iodine  may  readily  be 
detached  in  large  masses  and  removed  from  the  adapter.  It  should  be 
kept  in  a  wide-mouth,  glass-stoppered  bottle. 

Chlorine.     Cl. 

Chlorine  is  a  yellowish  gas  about  two  and  one-half  times  heavier  than 
air.  It  is  sparingly  soluble  in  water.  When  required  it  must  be  made. 
The  details  are  given  under  "  Determination  of  Silicon  in  Iron  and  Steel." 

Sulphurous  Acid.     H2SO3. 

To  make  sulphurous  acid  gas,  mix  powdered  charcoal  and  strong 
sulphuric  acid  until  a  thin  paste  is  formed,  heat  the  paste  in  a  flask,  very 
gently  at  first,  and  pass  the  gas  through  a  washing-bottle  containing  a 
little  water.  The  reaction  is  C  + 2H2SO4=CO2+ 2SO2  + 2H2O.  The 
tube  leading  from  the  flask  into  the  washing-bottle  should  have  a  bulb 
in  it  to  prevent  the  reflux  of  water  into  the  flask  in  case  of  sudden 
cooling.  The  aqueous  solution  of  the  gas  is  made  by  passing  the  washed 
gas  into  distilled  water.  The  gas,  SO2,  has  a  specific  gravity  of  2.21 
(air=i).  i  c.c.  of  water  at  15°  C.  dissolves  0.1353  gramme  of  SO2. 

Chromic  Acid.     CrO3. 

Chromic  anhydride  as  a  red  powder  or  in  the  form  of  scarlet  crystals 
is  easily  obtained  in  a  state  of  purity.  It  is  deliquescent,  and  dissolves  in 
a  small  quantity  of  water,  forming  a  dark  brownish-colored  liquid.  It 
may  be  made  by  pouring  I  volume  of  a  saturated  solution  of  bichromate 
of  potassium  into  ij£  volumes  of  strong  sulphuric  acid,  stirring  con- 
stantly. The  liquid  on  cooling  deposits  crimson  needles  of  chromic  an- 


36  THE    CHEMICAL   ANALYSIS   OF  IRON. 

hydride,  which    must   be   separated   from   the   mother-liquid   and   purified 
by  recrystallization. 

GASES. 
Carbonic  Acid  Gas.     CO2. 

The  best  form  of  generator  is  shown  in  Fig.  45.  It  was  first  sug- 
gested by  Casamajor.*  It  consists  of  a  large  tubulated  bottle,  the  bottom 
of  which  is  covered  to  the  depth  of  about  I  inch  (25  mm.)  with  buck- 
shot, on  top  of  which  rest  lumps  of  marble.  Dilute  hydrochloric  acid 
(i  acid  to  5  water)  is  admitted  through  the  tube  which  enters  at  the 
tubulure  at  the  bottom  of  the  bottle,  bending  down  so  as  to  reach  the 
bottom  of  the  bottle.  The  wash-bottle  A  contains  water.  By  blowing 
in  the  rubber  tube  attached  to  the  acid-bottle  the  acid  passes  over  into 
the  tubulated  bottle.  When  the  stopcock  K  is  closed,  the  pressure  in 
the  tubulated  bottle  forces  the  acid  back  into  the  acid-bottle.  When  the 
acid  becomes  exhausted  and  remains  in  the  tubulated  bottle,  pour  a 
little  strong  HC1  into  the  acid-bottle  and  blow  it  over  into  the  tubulated 
bottle.  The  generated  gas  will  force  the  liquid  back  into  the  acid-bottle, 
when  it  can  be  replaced  by  fresh  acid.  A  slightly  different  form  is 
shown  in  Fig.  48. 

Sulphuretted  Hydrogen  Gas.     H2S. 

The  same  form  of  apparatus  is  used  for  generating  H2S.  Ferrous 
sulphide  is  substituted  for  marble,  but  HC1  is  used  instead  of  H2SO4,  as 
is  generally  advised,  for  the  ferrous  sulphate  formed  crystallizes  out  and 
clogs  the  apparatus. 

Hydrogen.     H. 

The  same  form  of  apparatus  as  that  used  for  CO2  and  H2S  can  be 
used  to  advantage  for  generating  hydrogen  gas.  Pieces  of  zinc,  which 
may  be  obtained  by  melting  the  zinc  and  pouring  it  in  a  sheet  about 
^  inch  (6  mm.)  thick,  so  that  it  can  easily  be  broken,  are  to  be  used, 
and  not  granulated  zinc.  Hydrochloric  acid  is  better  than  sulphuric. 


*  American  Chemist,  vi.  209. 


REAGENTS.  ^ 

Oxygen  Gas.     O. 

Oxygen  compressed  in  cylinders  can  be  obtained  from  most  dealers 
in  chemicals,  but  it  should  always  be  carefully  tested  before  being  used 
for  the  determination  of  carbon  in  steel  or  iron,  as  the  cylinders  are 
sometimes  filled  with  coal-gas,  and  a  cylinder  wrhich  has  once  held  coal- 
gas  is  rarely  free  from  hydrocarbons. 

The  gas  may  be  made  on  a  small  scale  in  the  laboratory  by  carefully 
mixing  in  a  porcelain  mortar  100  grammes  chlorate  of  potassium  and  5 
grammes  powdered  binoxide  of  manganese,  transferring  to  a  retort,  which 
the  mixture  should  not  more  than  half  fill,  and  heating  carefully  over  a 
Bunsen  burner.  The  evolved  gas  may  be  collected  in  a  gas-holder  or 
in  an  india-rubber  bag.  The  latter  is  not  to  be  recommended  for  use 
for  carbon  determinations,  as  rubber  is  very  liable  to  give  off  hydro- 
carbons. 

ALKALIES   AND   ALKALINE    SALTS. 

Ammonia.     NH4HO. 

The  solution  of  ammonia  gas  (NH3)  commonly  used  is  of  sp.  gr.  0.88, 
and  contains  about  30  to  35  per  cent,  of  ammonia.  It  should  be  kept 
in  glass-stoppered  bottles  and  in  a  cool  place,  as  the  gas  passes  off  very 
rapidly  even  at  the  ordinary  temperature  when  open  to  the  air.  It 
should  be  colorless,  leave  no  residue  upon  evaporation,  be  free  from 
chlorides  and  sulphates,  and  give  no  precipitate  with  H2S. 

Bisulphite  of  Ammonium.     NH4HSO3. 

Bisulphite  of  ammonium  is  made  by  passing  sulphurous  acid  gas 
into  strong  ammonia  until  the  solution  becomes  yellowish  in  color  and 
smells  strongly  of  sulphurous  acid.  By  the  method  of  manufacture  of 
SO2  given  on  page  35,  a  large  amount  of  CO2  is  formed  at  the  same 
time,  which  is  absorbed  by  the  ammonia.  This  is  gradually  displaced 
by  the  SO2,  and,  if  the  solution  is  kept  cool,  white  crystals  of  the  neutral 
sulphite,  (NH4)2SO3,H2O,  are  deposited.  These  are  gradually  dissolved  by 
the  excess  of  SO2  until  the  solution  becomes  quite  clear,  assuming  a 


38  THE   CHEMICAL   ANALYSIS   OF  IRON. 

yellowish  tint.  By  exposure  to  air  bisulphite  of  ammonium  is  gradually 
oxidized  to  sulphate.  Old  bisulphite  of  ammonium  always  contains  a 
small  amount  of  hyposulphite,  which  occasions  a  precipitate  of  sulphur 
when  deoxidizing  solutions  of  ferric  salts.  It  is  difficult  to  purchase  pure 
bisulphite  of  ammonium,  and  bisulphite  of  sodium  is  very  apt  to  contain 
phosphoric  acid,  so  that  the  analyst  is  generally  obliged  to  manufacture 
this  reagent  for  himself.  When  made  from  strong  ammonia-water,  18  c.c. 
of  bisulphite  will  deoxidize  a  solution  of  10  grammes  of  iron  or  steel. 

Sulphide  of  Ammonium.     (NH4)2S. 

Sulphide  of  ammonium  is  made  by  saturating  strong  ammonia  with 
H2S  and  adding  an  equal  volume  of  ammonia.  The  reactions  are 

NH4HS  +  NH4HO  =  (NH4)2S  +  H2O. 
The  solution  becomes  yellow  by  age  or  by  exposure  to  the  air. 

Chloride  of  Ammonium.     NH4C1. 

Chloride  of  ammonium  is  a  white,  crystalline,  anhydrous  salt,  soluble  in 
about  its  own  weight  of  water  at  100°  C.,  and  in  2.7  parts  of  water  at  18°  C. 
It  is  volatilized  when  heated  without  previous  fusion.  The  salt  is  usually 
purified  by  sublimation.  It  generally  contains  a  little  iron,  but  is  free  from 
other  impurities.  To  prepare  chloride  of  ammonium  for  use  in  J.  Law- 
rence Smith's  method  for  decomposition  of  silicates,  dissolve  it  in  boiling 
water  and  evaporate  down  on  a  water-bath  or  air-bath.  When  the  salt 
begins  to  crystallize  out,  stir  vigorously.  The  crystals  formed  will  be  very 
small.  Drain  off  the  liquid  and  dry.  The  salt  can  then  be  readily  pow- 
dered. 

Nitrate  of  Ammonium.     NH4NO3. 

Nitrate  of  ammonium  is  a  white,  crystalline  salt,  soluble  in  one-half  its 
weight  of  water  at  18°  C.,  and  in  much  less  at  100°  C.  When  dissolved 
in  water  it  produces  great  cold.  By  evaporation  it  loses  ammonia  and 
becomes  acid.  When  heated  it  fuses  at  108°  C.,  and  is  decomposed  be- 
tween 230°  C.  and  250°  C.  into  water  and  nitrous  oxide,  NH4NO3=2H2O 
-j-  N2O.  It  should  leave  no  residue  when  volatilized. 


REAGENTS.  39 

Fluoride  of  Ammonium.     NH4P1. 

Fluoride  of  ammonium  may  be  made  by  saturating  hydrofluoric  acid  by 
ammonia.  The  salt  crystallizes  when  left  to  evaporate  over  quicklime.  It 
is  slightly  •  deliquescent,  and  therefore  difficult  to  keep,  as  the  solution 
attacks  glass. 

Acetate  of  Ammonium.     NH4C2H3O2. 

Acetate  of  ammonium  is  best  made  by  slightly  acidulating  ammonia 
by  acetic  acid.  One  volume  of  strong  ammonia-water  requires  about  2 
volumes  of  acetic  acid,  1.04  sp.  gr.,  to  neutralize  it.  It  is  best  to  make  it 
as  needed,  as  it  decomposes  when  kept. 

Oxalate  of  Ammonium.     (NH4)2C2O4  +  H2O. 

Oxalate  of  ammonium  is  a  white  salt,  crystallizing  in  long  prisms  united 
in  tufts.  It  is  soluble  in  3  parts  of  water  at  18°  C. 

Caustic  Soda.     NaHO. 

Fused  sodic  hydrate  purified  by  alcohol  is  sufficiently  pure  for  ordinary 
purposes.  It  forms  white  opaque  masses,  having  a  strong  affinity  for  water. 
It  dissolves  in  water  Vith  evolution  of  heat.  Pure  sodic  hydrate  is  prepared 
by  allowing  metallic  sodium  to  decompose  water  in  a  platinum  dish.  It 
must  be  kept  in  a  silver  or  platinum  bottle,  as  the  solution  acts  very 
rapidly  on  glass. 

Phosphate  of  Sodium  and  Ammonium.     NaNH4HPO4,4H2O. 

Phosphate  of  sodium  and  ammonium  (microcosmic  salt)  is  a  white,  crys- 
talline salt,  soluble  in  6  parts  of  cold  and  I  part  of  hot  water.  It  should  not 
be  kept  in  solution  for  any  great  length  of  time,  as  it  attacks  glass  very 
readily.  It  loses  its  water  of  crystallization  very  easily,  and  when  heated' 
gives  off  its  ammonia,  leaving  pure  metaphosphate  of  sodium,  which  in  the 
fused  condition  dissolves  metallic  oxides  in  many  cases  with  the  production 
of  characteristic  colors,  which  makes  it  a  valuable  reagent  for  blow-pipe 
analysis.  It  is  easily  obtained  in  a  state  of  purity. 


40  THE    CHEMICAL   ANALYSIS   OF  IRON. 

Carbonate  of  Sodium.     Na2CO3. 

Carbonate  of  sodium  is  never  quite  pure.  It  always  contains  small 
amounts  of  silica,  alumina,  lime,  and  magnesia,  besides  sulphuric  acid.  It 
may  generally  be  obtained  quite  free  from  phosphoric  acid.  Every  lot 
should  be  carefully  examined  for  all  the  above  impurities,  and  the  amount 
per  gramme  noted,  so  that  the  proper  subtraction  may  be  made  in  each 
analysis.  It  is  used  in  solution  only  for  the  neutralization  of  solutions,  as 
in  the  determination  of  manganese  by  the  acetate  method,  and  as  the  solu- 
tion attacks  glass  very  rapidly,  it  is  best  to  dissolve  the  salt  only  as  it  is 
needed. 

Nitrate  of  Sodium.     NaNO3. 

Nitrate  of  sodium  is  used  occasionally  instead  of  nitrate  of  potassium 
in  making  fusions  of  ores  containing  titanic  acid.  It  may  be  prepared 
by  acidulating  a  strong  solution  of  carbonate  of  sodium  with  nitric  acid, 
heating  until  the  water  and  excess  of  nitric  acid  are  driven  off,  and  powder- 
ing the  dry  salt. 

Hyposulphite  of  Sodium.     Thiosulphate   of  Sodium.     Na2S2O3-f  5H2O. 

Hyposulphite  of  sodium  is  very  soluble  in  water,  but  decomposes 
even  in  tightly-stoppered  bottles,  sulphate  of  sodium  being  formed  and 
sulphur  precipitated.  It  should,  therefore,  be  dissolved  only  as  used. 
The  ordinary  salt  of  commerce  is  sufficiently  pure  for  use. 

Acetate  of  Sodium.     NaC2H3O2  +  3H2O. 

Crystallized  acetate  of  sodium  dissolves  in  3.9  parts  of  water  at  6°  C. 
It  is  rarely  quite  pure,  containing,  usually,  calcium  salts,  but  it  may  be 
used  after  solution  and  filtration  for  partial  analyses,  as  in  the  determina- 
tion of  manganese  by  the  acetate  method,  etc.  In  complete  analyses  it 
is  better  to  use  acetate  of  ammonium.  When  the  use  of  acetate  of 
sodium  is  unavoidable,  it  can  be  made  by  dissolving  C.  P.  carbonate  of 
sodium  in  acetic  acid,  boiling  off  the  liberated  carbonic  acid,  and  adding 
acetic  acid  to  slight  acid  reaction. 


REAGENTS.  ^ 

Caustic  Potassa.     KHO. 

Caustic  potassa  purified  by  solution  in  alcohol,  filtration,  and  subse- 
quent evaporation  to  dryness  and  fusion,  is  quite  pure  enough  for  all  the 
ordinary  purposes  of  iron  analysis.  An  aqueous  solution  of  1.27  sp.  gr. 
is  used  to  absorb  carbonic  acid  in  the  determination  of  carbon  in  iron 
and  steel,  in  the  determination  of  carbonic  acid  in  ores,  etc.  300  grammes 
of  fused  KHO  dissolved  in  I  litre  of  water  will  give  a  solution  of  about 
this  strength. 

Nitrite  of  Potassium.     KNO2. 

Nitrite  of  potassium  is  used  to  separate  nickel  and  cobalt.  It  is  very 
difficult  to  buy  the  pure  salt,  but  it  is  easily  made  as  follows :  Heat  I 
part  of  nitrate  of  potassium  in  an  iron  dish  until  it  is  just  fused,  then 
add,  with  constant  stirring,  2  parts  of  metallic  lead.  Raise  the  heat 
slightly  to  complete  the  oxidation  of  the  lead,  and  allow  the  mass  to 
cool.  Treat  the  mass  with  water,  filter  from  the  oxide  of  lead,  pass  CO2 
through  the  solution  to  precipitate  the  greater  part  of  the  dissolved  lead, 
and  filter.  To  the  filtrate  add  a  little  sulphide  of  ammonium  to  precipi- 
tate the  last  traces  of  lead,  filter,  evaporate  to  dryness,  and  fuse  in  a 
platinum  dish  to  decompose  any  hyposulphite  that  may  have  been  formed, 
and  preserve  the  fused  salt  for  use.  Nitrite  of  potassium  is  deliquescent. 

Nitrate  of  Potassium.     KNO3. 

Nitrate  of  potassium  is  a  white,  crystalline  salt,  anhydrous,  and  soluble 
in  jy2  parts  of  water  at  o°  C,  and  in  0.4  part  of  water  at  100°  C.  It 
melts  below  a  red  heat  to  a  colorless  liquid,  and  at  a  red  heat  gives  off 
oxygen  gas  more  or  less  contaminated  by  nitrogen,  being  converted  into 
nitrite  and  oxide  of  potassium.  The  salt  may  be  purchased  in  a  sufficient 
state  of  purity  for  all  purposes  of  iron  analysis,  but,  as  it  may  contain 
small  amounts  of  sulphuric  acid,  the  amount  should  always  be  determined 
and  the  proper  allowance  made  when  it  is  to  be  used  for  the  estimation 

of  sulphur  in  ores. 

Sulphide  of  Potassium.     K2S. 

Sulphide  of  potassium  is  made  by  passing  H2S  into  a  solution  of 
caustic  potassa  and  filtering  from  any  precipitated  alumina  or  sulphide 

4 


42  THE    CHEMICAL   ANALYSIS   OF  IRON. 

of  iron.  It  is  used  instead  of  the  corresponding  ammonia-salt  when 
the  solution  contains  copper,  as  sulphide  of  copper  is  slightly  soluble 
in  sulphide  of  ammonium. 

Bichromate  of  Potassium.     K2Cr2O7. 

Bichromate  of  potassium  is  an  orange-colored,  anhydrous,  crystalline 
salt,  soluble  in  20  parts  of  water  at  o°  C,  and  in  i  part  of  water  at 
1  00°  C.  It  melts  below  a  red  heat  to  a  transparent  red  liquid,  crum- 
bling to  powder  upon  cooling.  Heated  with  strong  H2SO4  it  gives  off 
about  one-sixth  its  weight  of  oxygen  gas,  the  reaction  being  K2Cr2O7  + 
2H2SO4=Cr2K2(SO4)2  +  4H2O+3O.  It  is  readily  obtained  in  a  state  of 
purity,  but  should  always  be  fused  to  destroy  any  organic  matter  before 
being  used  to  determine  carbon  in  iron  or  in  ores. 

Chlorate  of  Potassium.     KC1O3. 

Chlorate  of  potassium  is  a  white,  crystalline,  anhydrous  salt.  It  is 
soluble  in  about  30  parts  of  water  at  o°  C.,  and  in  about  2  parts  at  100°  C. 
It  is  readily  decomposed  by  heat,  first  into  a  mixture  of  chloride  and  per- 
chlorate  of  potassium,  a  portion  of  the  oxygen  being  set  free,  and  at  a 
higher  temperature  the  remaining  oxygen  is  given  off,  chloride  of  potas- 
sium alone  remaining.  It  is  easily  obtained  in  a  sufficient  state  of  purity  for 
use  in  iron  analysis.  Heated  with  nitric  acid  it  yields  nitrate  and  perchlo- 
rate  of  potassium,  water,  chlorine,  and  oxygen,  thus  : 

8KClO3  +  6HNO3=6KNO3+2KClO4  +  6Cl+i3O-f  3H2O. 
Heated  with  hydrochloric  acid  it  gives  chloride  of  potassium,  water,  and 
a  mixture  of  peroxide  of  chlorine  and  chlorine,  called  eucklorine,  thus  : 


Bisulphate  of  Potassium.     KHSO4. 

Bisulphate  of  potassium  is  a  white,  crystalline  salt,  soluble  in  about  one- 
half  its  weight  of  boiling  water.  A  large  amount  of  water  decomposes  it 
into  sulphate  of  potassium  and  free  sulphuric  acid  ;  even  in  the  presence  of 
a  large  excess  of  sulphuric  acid  the  neutral  salt  crystallizes  out,  leaving  free 
sulphuric  acid  in  the  solution.  Bisulphate  of  potassium  melts  at  197°  C.  ; 


REAGENTS.  43 

at  higher  temperatures  it  gives  off  water,  leaving  the  anhydrous  salt,  and  at 
a  red  heat  it  gives  off  sulphuric  acid,  leaving  the  neutral  sulphate.  It  is 
difficult  to  obtain  it  very  pure,  but  it  may  be  made  as  follows :  Dissolve 
bicarbonate  of  potassium  in  water,  filter,  and  from  a  graduated  vessel  add 
H2SO4  until,  after  boiling  off  the  liberated  CO2,  the  solution  is  neutral,  or 
but  very  faintly  alkaline  to  test-paper.  Filter,  if  necessary,  and  to  the  fil- 
trate add  as  much  H2SO4  as  was  added  in  the  first  place  to  neutralize  the 
bicarbonate.  Boil  the  solution  down,  and  finally  fuse  the  mass  in  a  platinum 
dish.  Cool  it,  and  when  it  is  almost  ready  to  solidify  pour  it  into  another 
dish.  Break  it  up,  and  preserve  it  in  glass-stoppered  bottles. 

//   .* 
Iodide  of  Potassium.     KI. 

Iodide  of  potassium  is  a  white,  crystalline,  anhydrous  salt,  very  soluble  in 

•» 

water,  and  in  dissolving  causes  a  fall  of  temperature  in  the  solution.  It  is 
soluble  in  about  0.8  part  of  water  at  o°  C,  and  in  0.5  part  of  water  at 
I  OO°  C.  It  is  soluble  in  6  parts  of  alcohol  at  the  ordinary  temperature, 
and,  when  dissolved,  the  addition  of  HC1  does  not  turn  it  brown  if  it  is  free 
from  iodate.  A  solution  of  I  part  of  iodide  of  potassium  in  2  parts  of  water 
will  dissolve  2  parts  of  iodine,  but  upon  dilution  some  of  the  iodine  is 

precipitated. 

Permanganate  of  Potassium.     KMnO4. 

Permanganate  of  potassium  is  a  dark,  purple-red,  anhydrous  salt,  crys- 
tallizing in  long  needles.  It  is  soluble  in  16  parts  of  water  at  15°  C.  It  is 
easily  obtained  very  pure,  but  the  solution  should  always  be  filtered  through 
ignited  asbestos,  as  paper  has  a  strong  reducing  action  on  it. 

Ferrocyanide  of  Potassium.     K4Pe2Cy6 -j- SHgO. 

Ferrocyanide  of  potassium  is  a  yellow,  crystalline  salt,  soluble  in  4  parts 
of  water  at  o°  C.,  and  in  2  parts  of  water  at  100°  C.  It  is  used  as  a  reagent 
to  show  the  presence  of  ferric  salts,  which  produce  a  blue  coloration,  caused 
by  the  formation  of  ferrocyanide  of  iron  (Prussian  blue). 

Ferricyanide  of  Potassium.     K3Fe2Cy6. 

Ferricyanide  of  potassium  is  a  blood-red,  anhydrous,  crystalline  salt, 
soluble  in  about  3.1  parts  of  water  at  o°  C.,  and  in  1.3  parts  of  water  at 


44  THE   CHEMICAL   ANALYSIS  OF  IRON. 

1 00°  C.  The  dilute  solution,  like  that  of  the  ferrocyanide,  is  yellow  in 
color.  Ferrous  salts  added  to  the  solution  give  a  blue  coloration,  due  to 
the  formation  of  ferrous  ferricyanide,  while  ferric  salts  produce  no  change 
of  color.  The  ferricyanide  should  never  be  kept  in  solution. 

SALTS    OF   THE   ALKALINE    EARTHS. 
Carbonate  of  Barium.     BaCO3. 

Carbonate  of  barium  prepared  by  precipitation  is  a  soft  white  powder. 
It  is  difficult  to  obtain  it  in  a  state  of  purity,  but  it  is  easily  prepared 
by  adding  a  solution  of  carbonate  of  ammonium  to  a  clear  boiling  solu- 
tion of  chloride  of  barium,  washing  the  precipitated  carbonate  of  barium 
with  hot  water,  first  by  decantation  and  afterwards  on  a  filter.  The  car- 
bonate of  ammonium  should,  of  course,  be  free  from  sulphate.  The 
thoroughly  washed  carbonate  of  barium  should  be  transferred  to  a  bottle 
and  shaken  up  with  water,  in  which  condition  it  is  ready  for  use.  Car- 
bonate of  barium  is  very  slightly  soluble  in  water,  requiring,  according 
to  the  different  authorities,  from  4,000  to  25,000  parts  of  water  to  dis- 
solve it.  It  is  poisonous. 

Acetate  of  Barium.     Ba(C2H3O2)2. 

Acetate  of  barium  may  be  prepared  by  dissolving  pure  carbonate  of 
barium  in  acetic  acid.  It  crystallizes  with  I  or  3  atoms  of  water,  but 
dried  at  o°  C.,  or  exposed  to  the  air,  it  effloresces  and  yields  the  anhy- 
drous salt  as  a  white  powder.  It  is  very  soluble  in  water,  dissolving  in 
about  2  parts  of  water  at  o°  C.,  and  in  about  I  part  at  100°  C.  When 
heated  it  decomposes  into  acetone  and  carbonate  of  barium,  thus  : 
Ba(C2H3O2)2=C3H6O  +  BaCO3. 

Chloride  of  Barium.     BaCl2,2H2O. 

Chloride  of  barium  is  a  white,  crystalline  salt,  soluble  in  about  3  parts 
of  water  at  15°  C.,  and  in  about  ij^  parts  at  100°  C.  Heated  to 
1 00°  C.  it  loses  its  water  of  crystallization,  yielding  the  anhydride  as  a 
wThite  mass,  which  melts  at  a  full  red  heat.  Chloride  of  barium  is  almost 


REAGENTS.  ^ 

insoluble  in  strong  HCL  It  is  used  almost  exclusively  for  the  determina- 
tion of  sulphuric  acid,  and  may  be  kept  in  solution  for  this  purpose. 
100  grammes  of  the  crystallized  salt  dissolved  in  I  litre  of  water  is  a 
good  proportion  to  use.  Of  this  solution  10  c.c.  will  precipitate  1.16 
grammes  of  BaSO4,  equal  to  0.4  gramme  SO3  or  0.16  gramme  S. 

Caustic  Baryta.     Hydrate  of  Barium.     BaH2O2,8H2O. 

Hydrate  of  barium  is  a  white,  crystalline  salt,  soluble  in  20  parts  of 
water  at  15°  C,  and  in  3  parts  of  water  at  100°  C.  The  anhydride 
may  be  prepared  by  heating  nitrate  of  barium  to  redness  in  a  platinum 
crucible,  raising  the  heat  gradually  at  first  to  avoid  loss  from  frothing. 
It  attacks  platinum,  however,  at  a  high  temperature.  The  solution  has 
a  strong  affinity  for  carbonic  acid,  absorbing  it  readily  from  the  air,  the 
carbonate  of  barium  so  formed  causing  a  scum  on  the  surface  of  the 
solution.  The  solution  attacks  glass  very  strongly. 

Chloride  of  Calcium.     CaCl2. 

Crystallized  chloride  of  calcium  loses  all  its  water  of  crystallization 
at  200°  C.,  yielding  the  white  porous  anhydrous  chloride,  which  is  very 
deliquescent.  The  anhydrous  salt  fuses  at  a  low  red  heat,  but  is  partly 
changed  to  oxide.  For  this  reason  the  fused  salt  should  never  be  used 
for  drying  CO2  in  the  determination  of  this  gas,  as  some  of  it  is  taken 
up  by  the  oxide  of  calcium.  A  solution  of  chloride  of  calcium  containing 
59  parts  of  the  anhydrous  salt  to  100  parts  of  water  boils  at  115°  C.,  a 
saturated  solution  at  179.5°  C. 

Carbonate  of  Calcium.     CaCO3. 

Pure  carbonate  of  calcium,  for  use  in  Prof.  J.  Lawrence  Smith's  method 
for  the  determination  of  alkalies  in  silicates,  is  prepared  as  follows :  Dis- 
solve marble  or  calcite,  free  from  magnesia,  in  dilute  HC1,  add  an  excess 
of  powdered  marble,  heat  the  solution,  and  add  some  milk  of  lime  to 
precipitate  magnesia,  phosphate  of  calcium,  etc.  Filter,  heat  the  solution 
almost  to  boiling,  and  precipitate  by  carbonate  of  ammonium.  The  car- 


46  THE    CHEMICAL   ANALYSIS   OF  IRON. 

bonate  of  calcium  formed  will  be  a  very  dense  powder,  which  will  settle 
readily  and  be  easily  washed.  Wash  thoroughly,  dry,  and  preserve  for 
use. 

METALS   AND    METALLIC    SALTS. 

Metallic  Copper. 

Metallic  copper  absorbs  chlorine  gas  at  ordinary  temperatures,  and  is 
used  in  iron  analysis  to  absorb  any  chlorine  that  may  be  given  off  during 
the  combustion  of  the  carbonaceous  matter  liberated  by  the  action  of  sol- 
vents on  iron  and  steel.  It  is  used  in  the  form  of  drillings,  which  should  be 
taken  with  a  perfectly  dry  drill,  and  which  should  be  free  from  oil  and 
grease.  The  drillings  should  be  kept  in  a  stoppered  bottle,  and  may  be 
used  as  long  as  they  are  perfectly  bright  and  clean. 

Sulphate  of  Copper.     CuSO4,5H2O. 

Sulphate  of  copper  is  a  blue,  crystalline  salt,  soluble  in  2.7  parts  of  water 
at  18°  C,  and  in  0.55  part  of  water  at  100°  C.  The  aqueous  solution  of  the 
neutral  salt  is  strongly  acid  to  litmus-paper.  The  crystals  of  sulphate  of 
copper  effloresce  on  the  surface  when  exposed  to  the  air;  heated  to  100°  C. 
they  lose  4  atoms  of  water,  and  when  heated  to  200°  C.  they  lose  the 
remaining  atom.  The  anhydrous  salt  is  a  white  saline  mass,  which  is 
decomposed  at  a  bright-red  heat,  giving  off  sulphurous  acid  and  oxygen 
and  leaving  cupric  oxide.  The  anhydrous  salt  has  a  strong  affinity  for 
water,  and  also  for  hydrochloric  acid  gas.  A  solution  of  sulphate  of  cop- 
per dissolves  metallic  iron,  the  copper  being  precipitated  from  the  solution 
at  the  same  time  in  a  spongy  mass. 

Anhydrous  Sulphate  of  Copper  in  Pumice. 

The  property  anhydrous  sulphate  of  copper  possesses  of  absorbing 
hydrochloric  acid  gas  makes  it  useful  in  the  determination  of  carbon  by 
combustion,  and  it  is  best  prepared  for  this  purpose  as  follows :  Break  up 
some  pumice-stone  to  a  size  which  will  conveniently  go  into  a  Marchand  U 
tube,  and  after  separating  the  powder  place  the  pieces  in  a  porcelain  dish, 
and  pour  over  them  a  hot  saturated  solution  of  sulphate  of  copper.  Heat 


REAGENTS.  ^ 

the  dish  until  the  sulphate  of  copper  becomes  anhydrous,  which  will  be 
shown  by  the  disappearance  of  the  blue  color.  Transfer  the  pumice  while 
still  hot  to  a  dry,  glass-stoppered  bottle. 

Cupric  Chloride.     CuCl2-f  Aq. 

To  prepare  cupric  chloride  for  use  in  dissolving  iron  or  steel  for  the 
determination  of  carbon,  grind  up  equal  weights  of  sulphate  of  copper  and 
common  salt  in  a  porcelain  mortar,  and  pour  over  the  mixture  a  small 
amount  of  water  heated  to  50°—  60°  C.  The  liquid  becomes  emerald-green 
in  color,  and  deposits  upon  evaporation  sulphate  of  sodium.  Decant  from 
the  deposited  salt  and  evaporate  again  until  the  solution  is  reduced  to  a 
very  small  bulk.  Cool,  and  decant  from  the  remainder  of  the  sulphate  of 
sodium  and  the  excess  of  chloride  of  sodium.  By  further  evaporation  and 
cooling  the  cupric  chloride  may  be  obtained  in  the  form  of  green  crystals. 
These  crystals  are  deliquescent.  The  solution  should  be  diluted  and  filtered 
through  asbestos. 


Double  Chloride  of  Copper  and  Ammonium. 

The  double  chloride  of  copper  and  ammonium  is  a  bluish-green  crystal- 
line salt,  quite  soluble  in  water.  It  is  much  the  best  reagent  in  use  for  the 
solution  of  iron  and  steel  in  the  determination  of  carbon.  It  is  easily  ob- 
tained in  a  state  of  purity,  but  it  may  be  prepared  as  follows  :  Dissolve  53.4 
parts  of  chloride  of  ammonium  and  85.4  parts  of  crystallized  cupric  chloride 
in  as  little  water  as  possible,  evaporate  down,  and  allow  the  solution  to  cool. 
Drain  off  the  liquid,  evaporate  down,  and  get  another  crop  of  crystals. 
Dissolve  the  crystals  in  warm  water,  add  NH4HO  very  cautiously  until, 
after  stirring,  the  solution  remains  very  slightly  cloudy,  and  allow  it  to  cool 
and  settle.  Siphon  off  the  clear  solution,  and  filter  it  through  asbestos  into 
glass-stoppered  bottles,  when  it  will  be  ready  for  use. 

Oxide  of  Copper.     CuO. 

Oxide  of  copper,  both  fine  and  coarse,  for  combustions  is  easily  obtained. 
It  may  be  prepared  as  follows  :  Dissolve  metallic  copper  in  nitric  acid,  evap- 
orate to  dryness  in  a  porcelain  dish,  transfer  it  to  a  Hessian  crucible,  and 


4  8  THE    CHEMICAL   ANALYSIS   OF  IRON. 

heat  it  in  a  furnace  until  no  more  nitrous  fumes  are  given  off.  Keep  the 
crucible  well  covered  to  prevent  any  coal  getting  into  it,  and  avoid  raising 
the  heat  too  high,  or  the  mass  will  fuse.  Stir  it  from  time  to  time,  and  when 
finished  the  oxide  on  top  will  be  in  a  fine  powder,  while  that  in  the  bottom 
of  the  crucible  will  have  sintered.  Rub  it  up  in  a  mortar  and  pass  through 
a  fine  metal  sieve.  Keep  the  two  kinds,  fine  and  coarse,  separate  in  glass- 
stoppered  bottles,  carefully  covered  to  preserve  them  from  dust. 

Iron  "Wire. 

Very  fine  soft  piano-forte  wire  is  the  best  form  of  iron  to  use  when 
standardizing  solutions  of  permanganate  or  bichromate  of  potassium  by 
metallic  iron.  Wrap  one  end  of  a  piece  of  wire,  about  2  feet  (610  mm.) 
long,  around  a  lead-pencil,  and,  using  this  as  a  handle,  draw  the  wire 
several  times  through  a  piece  of  fine  emery-cloth,  then  through  a  fold 
of  dry  filter-paper,  then,  holding  the  wire  with  the  paper,  wrap  it  around 
the  pencil.  Cut  off  the  end  that  has  not  been  cleaned,  and  the  little 
spiral  of  wire  will  be  in  a  convenient  form  for  weighing. 

Ferrous  Sulphate.     FeSO4,7H2O. 

Ferrous  sulphate  (green  vitriol,  or  copperas)  is  a  bluish-green  crystal- 
line salt,  soluble  in  1.64  parts  of  water  at  10°  C.,  and  in  0.3  part  at  100°  C. 
'  It  is  insoluble  in  alcohol.  The  crystals  lose  6  atoms  of  water  when  heated 
to  1 14°  C.,  but  retain  the  last  atom  even  at  280°  C.  Heated  to  a  red  heat 
the  anhydrous  sulphate  is  decomposed,  giving  off  sulphurous  acid  and 
leaving  a  basic  ferric  sulphate,  which  at  a  higher  temperature  is  entirely 
decomposed,  leaving  only  ferric  oxide.  To  prepare  the  crystals  for  use  in 
volumetric  analysis,  add  alcohol  to  the  aqueous  solution  of  the  ferrous 
sulphate,  when  the  salt  is  precipitated  as  a  bluish-white  powder.  Filter, 
wash  with  alcohol,  dry  thoroughly,  and  preserve  in  glass-stoppered  bottles. 
The  salt  prepared  in  this  way  remains  unaltered  for  a  long  time. 

Double  Sulphate  of  Iron  and  Ammonium.     FeSO4(NH4)2SO4,6H2O. 

The  double  sulphate  of  iron  and  ammonium  is  a  light  green  crystalline 
salt,  soluble  in  2.8  parts  of  water  at  16.5°  C.  It  may  be  prepared  as 


REAGENTS.  ^ 

follows  :  Dissolve  276  grammes  of  crystallized  ferrous  sulphate  in  water, 
filter,  and  add  to  the  filtrate  a  clear  solution  of  sulphate  of  ammonium 
( (NH4)2SO4,  Glauber's  Sal  Secretum),  evaporate  down,  and  allow  the  double 
salt  to  crystallize  out.  Drain  the  crystals,  wash  slightly  with  cold  water, 
and  dry  on  blotting-paper.  When  perfectly  dry,  preserve  in  a  glass- 
stoppered  bottle.  The  crystals  remain  unaltered  for  a  long  time  even  in 
moist  air.  They  contain  exactly  \  their  weight  of  metallic  iron. 

Mercurous  Nitrate.     HgNO3,H2O. 

To  prepare  this  salt,  pour  cold,  moderately  strong  HNO3  on  an  excess 
of  metallic  mercury,  and  when  the  violent  action  has  subsided,  pour  off 
the  acid  and  allow  the  salt  to  crystallize  out  by  the  cooling  of  the  acid. 
The  salt  is  soluble  in  a  small  amount  of  water,  but  a  large  amount  de- 
composes it  into  a  basic  salt  and  free  acid. 

Mercuric  Oxide.     HgO. 

Mercuric  oxide  is  a  light  orange-yellow  substance  when  prepared  by 
precipitation  from  a  mercuric  salt.  To  a  dilute  solution  of  mercuric 
chloride  add  a  slight  excess  of  caustic  potassa,  allow  the  precipitate  to 
settle,  wash  it  thoroughly  by  decantation  with  hot  water,  and  finally  wash 
it  into  a  glass-stoppered  bottle.  It  is  used  shaken  up  with  water. 

Chromate  of  Lead.     PbCrO4. 

Fused  chromate  of  lead  is  a  dark  brown  mass  showing  a  radiated 
structure,  and  when  powdered  it  is  dark  yellow  in  color,  very  heavy, 
and  slightly  hygroscopic.  It  is  easily  obtained  very  pure,  but  may  be 
made  as  follows :  Dissolve  acetate  of  lead  in  water,  add  a  little  acetic 
acid,  filter,  and  precipitate  by  a  solution  of  bichromate  of  potassium. 
Wash  by  decantation,  and  finally  on  linen,  dry,  and  heat  in  a  Hessian 
crucible  until  the  mass  is  just  fused.  Pour  on  a  polished  iron  slab,  grind 
in  a  clean  mortar,  and  preserve  the  powder  in  glass-stoppered  bottles,  covered 
to  exclude  dust.  Chromate  of  lead  heated  to  a  full  red  heat  gives  off 
oxygen  and  is  reduced  to  a  mixture  of  basic  chromate  of  lead  and  oxide 
of  chromium. 


$0  THE    CHEMICAL   ANALYSIS   OF  IRON. 

Peroxide  of  Lead.     PbO2. 

Peroxide  of  lead  is  rather  difficult  to  obtain  in  a  state  of  purity  ;  it 
is  liable  to  contain  nitrate  of  lead  and  oxide  of  manganese.  The  latter 
element  interferes  materially  with  its  use  as  a  reagent  in  the  determina- 
tion of  manganese  by  the  color  test.  It  should  always  be  carefully  ex- 
amined by  boiling  with  dilute  nitric  acid,  and,  if  it  imparts  any  color  to 
the  solution,  must  be  promptly  rejected.  It  may  be  readily  prepared  by 
digesting  red  oxide  of  lead  in  dilute  nitric  acid,  decanting  off  the  nitrate 
of  lead,  and  washing  the  residue  thoroughly  with  hot  water.  Red  oxide 
of  lead  by  this  treatment  is  decomposed  into  protoxide  of  lead,  which 
dissolves  in  the  nitric  acid  and  peroxide,  which  remains  insoluble.  Per- 
oxide of  lead  is  a  heavy  brown  powder,  which,  when  heated,  gives  off 
oxygen  and  is  converted  into  red  lead  or  protoxide  of  lead. 

Oxide  of  Lead  dissolved  in  Caustic  Potassa. 

Pour  a  cold  solution  of  nitrate  of  lead  into  caustic  potassa,  1.27  sp.  gr., 
stirring  constantly  to  dissolve  the  oxide  of  lead,  which  precipitates.  Add 
the  nitrate  of  lead  until  a  permanent  precipitate  is  produced.  Allow  this  to 
settle,  and  siphon  the  clear  liquid  into  a  glass-stoppered  bottle.  It  is  well  to 
coat  the  stopper  with  a  little  paraffine,  to  prevent  its  sticking. 

Platinic  Chloride  Solution. 

Dissolve  platinum-foil  in  HC1,  adding  HNO3  from  time  to  time,  evaporate 
to  dry  ness  on  the  water-bath,  redissolve  in  HC1,  and  evaporate  again  to 
drive  off  the  HNO3.  Redissolve  in  water  with  the  addition  of  a  few  drops 
of  HC1,  filter,  and  preserve  in  a  bottle  the  stopper  and  neck  of  which  are 
protected  by  a  ground-glass  cap  to  prevent  any  access  of  ammonia  to  the 
solution. 

Metallic  Zinc. 

Melt  zinc,  which  should  be  as  free  as  possible  from  lead  and  iron,  in  a 
Hessian  crucible,  and  pour  it  in  a  thin  stream  from  a  height  of  four  or  five 
feet  into  a  bucket  of  cold  water,  giving  the  crucible  a  circular  motion  to 


REAGENTS.  5I 

prevent  the  zinc  from  falling  in  exactly  the  same  place  all  the  time.     Pour 
off  the  water,  dry  the  granulated  zinc,  and  preserve  it  in  bottles  for  use. 

Oxide  of  Zinc  in  Water. 

Emme'rton*  suggests  the  following  method  of  preparing  this  reagent: 
Dissolve  ordinary  zinc  white  in  HC1,  add  the  zinc  white  until  there  is 
an  excess  which  will  not  dissolve,  then  add  a  little  bromine-water,  heat 
the  solution,  filter,  and  precipitate  the  oxide  of  zinc  by  ammonia,  being 
careful  to  avoid  an  excess.  Wash  thoroughly  by  decantation,  and  then 
wash  into  a  bottle.  Shake  the  bottle  well,  to  diffuse  the  oxide  through 
the  water,  before  using. 

REAGENTS    FOR    DETERMINING   PHOSPHORUS. 

Magnesia  Mixture. 

Dissolve  1 10  grammes  of  crystallized  chloride  of  magnesium  (MgCl2 
-f6H2O)  or  50  grammes  of  the  anhydrous  salt  in  water,  and  filter.  Dis- 
solve 28  grammes  of  chloride  of  ammonium  in  water,  add  a  little  bro- 
mine-water and  a  slight  excess  of  ammonia,  and  filter.  Add  this  solution 
to  the  solution  of  chloride  of  magnesium,  add  enough  ammonia  to  make 
the  solution  smell  decidedly  of  ammonia,  dilute  to  about  2  litres,  transfer 
to  a  bottle,  shake  vigorously  from  time  to  time,  allow  to  stand  for  several 
days,  and  filter  into  a  small  bottle  as  required  for  use.  10  c.c.  of  this 
solution  will  precipitate  about  0.15  gramme  P2O5. 

Molybdate  Solution. 

Dissolve  100  grammes  of  molybdic  acid  in  422  c.c.  of  ammonia,  0.95  sp. 
gr.,  then  add,  with  constant  stirring,  1250  c.c.  of  nitric  acid,  1.2  sp.  gr.  Or 
to  123  grammes  of  crystallized  molybdate  of  ammonium  add  333  c.c.  of 
ammonia,  0.95  sp.  gr.,  and  62  c.c.  of  water.  To  this  solution  add  1250  c.c. 
of  nitric  acid,  1.2  sp.  gr.,  with  constant  stirring.  Allow  the  molybdate  so- 
lution to  stand  for  several  days,  and  siphon  off  the  clear  liquid  for  use. 


*  Trans.  Am.  Inst.  Min.  Engineers,  vol.  x.  p.  201. 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


* 


\    METHODS  FOR  THE  ANALYSIS 

OF 

PIG-IRON,  BAR-IRON,  AND  STEEL 


DETERMINATION    OF    SULPHUR. 

By  Evolution  as  H2S. 

KARSTEN  was  the  first  to  suggest  dissolving  iron  or  steel  in  HC1, 
or  dilute  H2SO4,  and  collecting  the  evolved  H2S  by  absorbing  it  in 
a  solution  of  a  metallic  salt.  He  recommended  CuCl2. 

Absorption  by  Alkaline  Solution  of  Nitrate  of  Lead. 
The  apparatus,  Fig.  45,  shows  the  usual  arrangement  for  carry- 
ing out  the  process,  with  the  addition  of  the  generating-bottles  for 
supplying  hydrogen  gas.  This  is  the  apparatus  described  under 
the  head  of  "  Apparatus  for  Generating  CO2,"  page  36.  The 
wash-bottle  A  contains  an  alkaline  solution  of  nitrate  of  lead,  Description 

of  the  ap- 

and  is  connected  with  the  funnel-tube  by  the  rubber  tube  B,  and     paratus. 
a  small  piece  of  glass  tubing,  C,  turned  at  a  right  angle  with  one 
end  drawn  down  and  covered  with  a  short  piece  of  rubber  tubing. 
This  fits  in  the  neck  of  the  bulb  of  the  funnel-tube  and  makes  a 
tight  joint.     The  analytical  process  is  conducted  as  follows : 

Weigh  10  grammes  of  borings  or  drillings,  free  from  lumps,  into    Description 

of  the 

the  previously  dried  flask  D,  and  close  it  with  the  rubber  stopper     process, 
fitted  with  the  funnel-tube  E  and  a  delivery-tube.     The  small  flask 
F  serves  as  a  condenser,  and  is  fitted  with  an  inlet-tube  reaching 
almost  to  the  surface  of  a  small  amount  of  water  in  the  bottom  of 

53 


54  THE    CHEMICAL   ANALYSIS   OF  IRON. 

the  flask,  a  safety-tube,  G,  dipping  just  below  the  surface  of  the 
water,  and  an  exit-tube  connected  with  the  first  of  the  two  wide- 
mouth  bottles  H.  In  each  of  the  bottles  H  are  poured  about  20 
or  30  c.c.  of  potassium  hydrate  solution  of  nitrate  of  lead*  and 
enough  water  to  fill  them  two-thirds  full.  Connect  the  apparatus, 
and  run  a  slow  stream  of  hydrogen  through  until  all  the  air  is 
expelled,  then  close  the  glass  stopcock  of  the  funnel-tube,  and 
shut  off  the  supply  of  hydrogen  by  closing  the  small  glass  stop- 
cock K.  If  the  connections  are  all  tight,  the  water  in  the  safety- 
tube  G  will  keep  its  level.  When  this  is  assured,  disconnect  the 
tube  C,  and  fill  the  bulb — which  should  be  of  about  100  c.c. 
capacity — with  a  mixture  of  50  c.c.  strong  HC1  and  50  c.c.  water. 
Replace  the  tube  C,  turn  on  the  hydrogen,  and  open  the  stop- 
cock of  the  funnel-tube,  so  as  to  allow  the  acid  to  flow  drop  by 
drop  into  the  flask  D.  When  the  acid  has  all  run  into  the  flask, 
regulate  the  flow  of  the  hydrogen  so  that  the  gas  will  continue  to 
pass  through  the  solutions  in  the  bottles  H,  H,  at  the  rate  of  6  or 
8  bubbles  a  second,  and  heat  the  flask  D  very  cautiously.  When 
the  solution  in  the  flask  D  has  boiled  for  a  few  minutes,  and  all 
the  metal  has  dissolved,  remove  the  source  of  heat  and  continue 
the  current  of  hydrogen  for  about  ten  minutes,  regulating  its  flow 
by  means  of  the  stopcock  K,  to  prevent  any  reflux  of  the  liquid 
in  H,  which  might  be  caused  by  the  cooling  of  the  flask  D.  Shut 
off  the  hydrogen,  disconnect  the  apparatus,  and  wash  the  contents 
of  the  bottle  H  into  a  No.  2  Griffin's  beaker.  Unless  a  precipi- 
tate of  sulphide  of  lead  appears  in  the  second  bottle  H,  it  need 
not  be  emptied,  but  the  same  solution  can  be  used  over  again  for 
the  next  analysis.  Collect  the  precipitate  in  a  small  filter,  wash  it 
once  or  twice  with  hot  water,  and,  while  still  moist,  throw  the  filter 
and  precipitate  back  into  the  beaker,  in  which  have  been  placed 
just  the  instant  before  some  powdered  KC1O3  and  from  5  to  20 
c.c.  strong  HC1,  according  to  the  amount  of  the  precipitate  of  lead 

*  See  page  50. 


ANALYSIS   OF  IRON  AND   STEEL. 

sulphide.  Allow  it  to  stand  in  a  cool  place  until  the  fumes  shall 
have  partly  passed  off,  then  add  about  twice  its  volume  of  hot 
water,  and  filter  into  a  No.  I  beaker.  Wash  with  hot  water,  heat 
the  filtrate  to  boiling,  and  add  NH4HO  until  the  solution  is 
slightly  alkaline  to  litmus-paper.  Acidulate  with  a  few  drops  of 
HC1,  add  5  to  10  c.c.  BaCl2  solution,*  boil  for  a  few  minutes,  and 
stand  aside  in  a  warm  place  overnight.  Filter  the  precipitate  of 
BaSO4,  preferably  on  a  Gooch  perforated  crucible,  wash  with  hot  Baso. 
water,  ignite,  and  weigh  as  BaSO4,  which  contains  13.73  Per 
cent.  S.  It  is  always  well  to  test  the  alkaline  filtrate  from  the  lead 
sulphide  with  a  few  drops  of  the  lead  solution,  for  it  might  happen 
that  all  the  lead  would  be  precipitated  from  the  solution  as  sul- 
phide, and  an  excess  of  H2S  remain  in  the  solution  as  sulphide  of 
potassium. 

Absorption  by  Ammoniac  al  Solution  of  Nitrate  of  Silver. 

Berzelius  proposed  the   use  of  a  dilute  solution  of  nitrate  of 
silver  made  alkaline  by  ammonia.     The  method  of  procedure  is 
as  follows  :   Dissolve  I  gramme  of  AgNO3  in  a  small  quantity  of  Preparation 
water,  and  make  it  strongly  alkaline  with  NH4HO;  pour  about     LliacT 
two-thirds  of  the  solution  into  the  first  of  the  bottles  D,  and  the     ^°n  * 
remainder  into  the  second,  and   fill  up  to  the  proper  level  with      silver- 
water.     Proceed  exactly  as  described  above  until  the  sulphide  of  Details  of  the 
silver  has  been  filtered  off  and  washed.     Dry  this  precipitate  care- 
fully at  a  low  temperature,  say  100°  C,  and  brush  it  carefully  into 
a  small,  dry  beaker,  returning  the  filter  to  the  funnel.     Pour  into 
the  bottles  D,  should  any  of  the  sulphide  remain  adhering  to  the 
sides,  20  or  30  c.c.  strong  HNO3,  and  when  it  is  all  dissolved,  pour 
the  acid  in  the  filter,  allowing  it  to  run  into  the  beaker  containing 
the  sulphide  of  silver,  and  wash  out  the  bottles  with  a  little  HNO3, 
allowing  this  to  run  over  the  filter  also.     Digest  the  sulphide  of 
silver  until  it  is  all  dissolved,  then  dilute  with  hot  water,  add  an 

•         *  See  page  44. 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Advantage 
of  this 
method. 

Disadvan- 
tage. 


Description 
of  appa- 
ratus. 


Details  of 
the 
method. 


Insolubility 
of  BaSO4 
in  NH4C1. 


excess  of  HC1,  and  filter  off  the  chloride  of  silver.  Add  a  small 
amount  of  carbonate  of  sodium,  and  evaporate  nearly  dry,  dilute,  add 
a  few  drops  of  HC1,  filter  if  necessary,  and  precipitate  as  before  by 
chloride  of  barium.  Even  when  the  sample  contains  no  sulphur  a 
slight  precipitate  of  carbide  of  silver  may  be  thrown  down  by  the 
carburetted  hydrogen  evolved  from  the  iron  or  steel  by  the  action 
of  the  acid. 

Absorption  and  Oxidation  by  Bromine  and  HCl. 
Fresenius*  suggested  passing  the  evolved  gases  through  a 
solution  of  bromine  in  HCl,  which  has  the  advantage  of  oxidiz- 
ing the  sulphuretted  hydrogen  at  once,  but  the  disadvantage  of 
filling  the  room  with  bromine-fumes  unless  the  apparatus  is  placed 
under  a  hood  with  a  good  draft.  It  is  necessary  when  using  this 
method  to  avoid  bringing  the  bromine-fumes  in  contact  with 
rubber  stoppers.  Instead  of  the  bottles  D,  attach  to  the  exit-tube 
a  bulb-tube  of  the  shape  shown  in  Fig.  46,  containing  3  to  5 

c.c.  of  bromine  and  enough  HCl  to  fill 
the  bulb-tube  to  the  marks  shown  in 
the  cut.  When  the  operation  is  fin- 
ished, wash  the  contents  of  the  bulb- 
tube  out  into  a  beaker,  heat  until  the 
bromine  is  all  driven  off,  neutralize  by 
NH4HO,  and  precipitate  the  sulphuric 
acid  exactly  as  described  on  page  55. 
Instead  of  neutralizing  by  NH4HO,  the 
HCl  solution  may  be  evaporated  down 
nearly  to  dryness  after  adding  a  little 
carbonate  of  sodium  or  the  solution  of  chloride  of  barium ;  but 
repeated  experiments  have  shown  that  sulphate  of  barium  is  prac- 
tically insoluble  in  chloride  of  ammonium,  so  that  the  plan  of 
neutralizing  by  NH4HO,  being  the  shorter  and  less  troublesome, 
is  to  be  preferred. 


FIG.  46. 


*  Fresenius,  Zeitschrift,  xiii.  37. 


ANALYSIS   OF  IRON  AND   STEEL.  ^ 

Absorption  and  Oxidation  by  Permanganate  of  Potassium. 
Drown  *  suggested  the  use  of  permanganate  of  potassium  solu- 
tion as  an  absorbent  and  oxidizer ;  the  process  being  carried  out 
as  follows :    Make  a  solution   of   permanganate   of   potassium,   5   Details  of 
grammes  to  the  litre  of  water,  and  fill  the  bottles  D  to  their  proper     ceL*™ 
height  with  this  liquid,  using  three  bottles,   however,  instead  of 
tAvo,  and  proceed  with  the  operation  as  before  described,  being 
careful  to  avoid  a  rapid  evolution  of  the  gas.     Wash  the  contents  Avoid  rapid 
of  the  bottles  D  into  a  clean  beaker,  dissolve  any  oxide  of  man-     J  gas' 
ganese  that  may  adhere  to  the  sides  of  the  bottles  in  HC1,  add 
this  to  the  solution  in  the  beaker,  and  then  add  enough  HC1  to 
decompose  the  permanganate  entirely.     Boil  until  the  solution  is 
colorless,  filter  if  necessary,  and  precipitate  by  chloride  of  barium. 
Allow  it  to  stand  overnight,   filter,  wash,  ignite,  and  weigh  the 
BaSO4. 

Absorption  and  Oxidation  by  Peroxide  of  Hydrogen. 
Craig  f  suggested  the  use  of  ammoniacal  solution  of  peroxide 
of  hydrogen   in   the  absorbing-bottles.      Attach  to  the  exit-tube  Details  of 
of  the  flask  B  (Fig.  45)  a  nitrogen-bulb  of  the  usual  form  (Fig.     method. 
46),  in  which  have  been  placed  4  c.c.  of  peroxide  of  hydrogen  and 
1 6  c.c.  of  ammonia,  and  proceed  as  before  directed.     When  the 
operation  is  finished,  wash  the  contents  of  the  nitrogen-bulb  into  Necessity 
a  small  beaker,  acidulate  slightly  with  HC1,  boil,  add  chloride  of     deter-  ° 
barium,  and  determine  the  amount  of  BaSO,  as  usual.     As  per-     mimng 

*  amount  of 

oxide  of  hydrogen  always    contains   sulphuric  acid,  the  amount     sulPhurfc 

acid  in 

must  be  carefully  determined  in  each  fresh  lot  of  the  H2O2,  and     peroxide 

of  hydro- 

the  proper  correction  made  for  the  volume  used.  gen. 

By  Oxidation  and  Solution. 
Many  chemists   still  prefer  the  old   method  of  oxidizing  and 

This  method 

dissolving  the  metal  and  precipitating  the  sulphuric  acid  in  the     preferred 
solution  by  chloride  of  barium.     The  details  are  as  follows  :  Treat 

*  Journal  Inst.  Min.  Engineers,  ii.  224.  f  Chem.  News,  xlvi.  199. 

5 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


Precautions 

necessary 

in  dissoiv- 


s°' 


Further  de- 


iron  it  is  to 

be  fused 

with 

Na2co3. 


5  grammes  of  drillings  in  a  No.  4  Griffin's  beaker,  covered  by  a 
watch-glass  with  40  c.c.  of  strong  HNO3.  This  requires  care,  for 
drillings  of  bar-iron  and  low  steel  are  often  acted  on  so  violently, 
even  by  strong  HNO3,  as  to  cause  the  solution  to  boil  over.  In 
this  case  it  is  best  to  place  the  beaker  in  a  dish  containing  a  little 
cold  water  and  to  add  the  acid  gradually.  When  all  the  acid  has 
been  added  and  the  action  has  ceased,  some  small  particles  gener- 
ally remain  undissolved,  and  their  solution  is  effected  by  heating 
the  beaker  on  the  sand-bath  and  finally  by  adding  a  few  drops 
of  HC1.  With  pig-iron  and  steel  there  is  usually  no  action  in 
the  cold,  and  in  this  case  heat  the  beaker  carefully  until  the  action 
begins,  then  stand  the  beaker  in  a  cooler  place,  and  if  the  action 
becomes  very  violent,  stand  the  beaker  in  cold  water  until  it 
moderates.  Very  high  carbon  steels  dissolve  with  great  difficulty 
even  in  boiling  acid  ;  but  the  solution  may  be  hastened  by  adding 
a  few  drops  of  HC1  from  time  to  time.  When  solution  is  com- 
plete and  only  particles  of  graphite  and  silica  remain  undissolved, 
which  is  shown  by  the  residue  being  entirely  flotant,  remove  the 
cover,  add  a  little  carbonate  of  sodium,  and  evaporate  the  solution 
to  dryness  in  the  air-bath.  The  addition  of  the  carbonate  of 
sodium  is  to  prevent  any  possible  loss  of  sulphuric  acid,  which 
might  otherwise  occur  by  the  decomposition  of  the  sulphate  of 
iron  at  3.  high  temperature.  Remove  the  beaker  from  the  air- 
bath,  and  when  cold  add  30  c.c.  HC1,  and  heat  until  the  oxide  of 
iron  is  dissolved,  evaporate  again  to  dryness  to  render  the  silica 
insoluble,  redissolve  in  as  little  HC1  as  possible,  dilute,  and  filter. 
Heat  the  filtrate  to  boiling,  add  5-10  c.c.  solution  of  chloride  of 
barium,  and  allow  it  to  stand  in  a  warm  place  overnight.  Filter, 
wash  with  a  little  dilute  HC1,  and  finally  with  hot  water;  dry, 
ignite,  and  weigh  as  BaSO4.  If  this  ignited  precipitate  is  red- 
^j  ^  jn  coior  jt  snOws  that  Fe2Oo  has  been  precipitated  with  the 
BaSO4.  In  this  case  fuse  with  Na2CO3,  dissolve  in  water,  filter, 
acidulate  the  filtrate,  and  precipitate  as  before. 


ANALYSIS   OF  IRON  AND  STEEL. 


Special  Precautions  in  the  Determination  of  Sulphur  in  Pig- 
Iron. 

Although  it  sometimes  happens  that  the  carbonaceous  residue 
left  after  treating  pig-iron  with  HC1  contains  no  sulphur,  as  a  rule 
it  contains  enough  to  affect  seriously  the  accuracy  of  the  analysis. 
It  is  not  only  in  the  case  of  cupriferous  pig-irons  that  this  occurs, 
but  sometimes  in  pig-irons  quite  free  from  copper,  and  nearly 
always  in  those  containing  titanium.  When  an  accurate  deter- 
mination of  sulphur  in  pig-iron  is  required,  the  examination  of  the 
carbonaceous  residue  should  never  be  neglected  when  the  evolution 
mctJiod  has  been  used. 

Transfer  the  residue  and  solution  from  the  flask  A,  page  54, 
to  a  clean  beaker,  and  filter,  using  the  pump  and  cone,*  with  a 
strong  filter-paper,  and  wash  thoroughly,  first  with  a  little  dilute 
HC1,  and  then  with  water.  Dry  the  residue  on  a  filter,  brush  it 
into  a  small  porcelain  mortar,  rejecting  the  filter,  and  grind  it  up 
with  10  grammes  dry  Na2CO3  and  5  grammes  KNO3.  Transfer  it 
to  a  large  platinum  crucible,  and  heat  it  gradually  until  it  is  fused. 
Run  the  fused  mass  well  up  in  the  sides  of  the  crucible,  allow  it  to 
cool,  fill  the  crucible  nearly  full  with  hot  water,  and  stand  it  over  a 
very  low  light  for  a  few  minutes.  If  the  crucible  is  large  enough, 
the  fusion  will  dissolve  completely  ;  if  not,  decant  the  liquid  into  a 
beaker,  fill  the  crucible  with  hot  water  again,  and  repeat  the  opera- 
tion until  the  crucible  is  quite  clean.  It  will  usually  be  stained 
somewhat ;  but  this  is  of  no  importance,  and  the  stain  can  be  re- 
moved afterwards  by  a  little  HC1.  Filter  the  aqueous  solution, 
wash  the  beaker  and  filter  a  few  times  with  hot  water,  acidulate 
the  filtrate  carefully  with  HC1,  and  evaporate  to  dryness  in  the  air- 
bath.  Redissolve  in  hot  water  with  a  little  HC1,  filter,  heat  the 
filtrate  to  boiling,  precipitate  by  BaCl2  solution,  allow  to  stand  in  a 
warm  place  overnight,  filter,  and  weigh  the  BaSO4.  As  it  is  im- 
possible to  get  Na2CO3  and  KNO3  absolutely  free  from  sulphur,  a 


Residue 
solution  of 


S- 


fusion  with 


KN°8' 


Necessity 
noted  for 


and  KN08 

fors. 


*  See  page  21. 


6o  THE   CHEMICAL   ANALYSIS   OF  IRON. 

blank  determination  should  be  made  for  each  new  lot  of  these 
reagents,  and  the  amount  of  BaSO4  found  subtracted  from  the 
amount  obtained  by  the  fusion  of  the  residue,  the  remainder  being 
calculated  to  S  and  added  to  the  amount  evolved  as  H2S.  In- 
stead of  fusing  the  carbonaceous  residue,  it  may,  after  drying,  be 
Treatment  of  brushed  into  a  small,  clean  beaker  and  treated  with  aqua  regia, 

residue 

with  aqua  evaporated  to  dryness,  redissolved  in  a  little  water  and  a  few 
drops  of  HC1,  filtered,  and  the  sulphuric  acid  precipitated  by 
BaCl2  solution,  with  the  usual  precautions.  The  fusion  method 
is,  however,  to  be  preferred. 


RAPID    METHOD. 

Volumetric  Determination  by  Iodine. 

This  method,  suggested  by  Elliott,*  involves  the  evolution  of 
the  sulphur  as  H2S,  its  absorption  in  a  solution  of  sodium  hy- 
drate, and  titration  by  iodine  in  iodide  of  potassium.  It  requires 
a  standard  solution  of  iodine,  a  standard  solution  of  hyposulphite 
of  sodium,  a  starch  solution,  and  a  standard  solution  of  bichro- 
mate of  potassium. 

Iodine  Solution. 

Dissolve  6.5  grammes  pure  iodine  in  water  with  9  grammes 
iodide  of  potassium,  and  dilute  to  I  litre. 

Hyposulphite  of  Sodium  Solution. 

Dissolve  25  grammes  hyposulphite  of  sodium  in  water,  add 
2  grammes  carbonate  of  ammonium,  and  dilute  to  I  litre.  The 
carbonate  of  ammonium  retards  the  decomposition  of  the  hypo- 
sulphite of  sodium. 

Starch  Solution. 

Weigh  out  into  a  porcelain  or  Wedgwood  mortar  I  gramme 
pure  wheat  starch,  and  rub  it  to  a  thin  cream  with  water.  Pour  it 

*  Chem.  News,  xxiii.  61. 


ANALYSIS   OF  IRON  AND   STEEL.  fa 

into  150  c.c.  boiling  water,  allow  it  to  stand  until  cold,  and  decant 
the  clear  solution.  The  addition  of  10  or  15  c.c.  glycerine  makes 
the  solution  keep  better.  It  is  better,  however,  to  make  a  fresh 
starch  solution  every  few  days. 

Bichromate  of  Potassium  Solution. 

Dissolve  5  grammes  pure  bichromate  of  potassium  in  water, 
and  dilute  to  I  litre. 

All  these  solutions  should  be  placed  in  glass-stoppered  bottles 
and  kept  in  a  dark  place. 

Standardizing-  the  Solutions. 

Standardize  the  bichromate  solution  as  directed  in  the  "  Anal- 
ysis of  Iron    Ores."      When   bichromate  of  potassium   is  added  Reaction 
to   iodide  of  potassium  in  presence  of  free  HC1,  iodine  is  liber-  Cr2o7is2 
ated,    in    accordance   with    the   formula    K2Cr2O7  +  6KI+ I4HC1  ^£ 
=  8KC1  +  Cr2Cl6+  ;H2O  +  61,  or  i  equivalent  of  K2Cr2O7=  294.4  excess of 

HCl. 

liberates  6  equivalents  of  iodine  =761.1.  Therefore,  by  adding  to 
a  solution  of  iodide  of  potassium  in  the  presence  of  HCl  a 
known  amount  of  bichromate,  we  can  calculate  the  absolute 
amount  of  iodine  liberated,  and  by  titrating  this  solution  by  the 
hyposulphite  solution  we  can  accurately  standardize  the  latter. 
The  reaction  which  takes  place  when  a  solution  of  hyposulphite  Reaction  of 
(thiosulphate)  of  sodium  is  acted  on  by  iodine  is  2NaHS2O3+ 
2l  =  2HI-fNa2S4O6,  or  2  equivalents  of  thiosulphate  unite  with 
2  equivalents  of  iodine  to  form  hydriodic  acid  and  tetrathionate  of 
sodium.  By  adding  a  few  drops  of  starch  solution  to  a  solution 
containing  iodine,  blue  iodide  of  starch  is  formed,  and  colors  the 
solution  as  long  as  it  contains  free  iodine.  When  enough  hypo- 
sulphite is  added  to  a  solution  of  this  kind  to  combine  exactly  with 
the  iodine,  the  blue  color  disappears.  Conversely,  upon  adding  a 
solution  of  iodine  to  a  solution  containing  hyposulphite  of  sodium 
and  a  little  starch,  the  sensitive  blue  color  of  the  iodide  of  starch 
will  disappear  as  fast  as  formed  until  all  the  thiosulphate  has  been 


62  THE   CHEMICAL  ANALYSIS   OF  IRON. 

changed  to  tetrathionate,  and  then  the  first  drop  of  iodine  in  excess 
Reaction  be-  will  change  the  solution  to  a  permanent  blue.     The  same  thing 

tween  sul- 
phuretted   holds  true  as  regards  a  solution  containing  free  H2S,  the  reaction 

anf08       being  H2S  -f  2!  =  2HI  +  S.     Proceed  therefore  as  follows  :  Dissolve 
about  I  gramme  of  pure  iodide  of  potassium  in  300  c.c.  water,  add 

5  c.c.  HC1,  and  then  25  c.c.  of  the  bichromate  solution,  which  will 
standard-      liberate  a  known  amount  of  iodine.     Drop  in  now  the  hyposulphite 

izing  the  *  V 

hyposui-     solution  from  a  burette  until  the  iodine  nearly  disappears,  add  a 

phite  solu-     _ 

don.          iew  drops  of  starch  solution,  and  continue  the  hyposulphite  until 

the  blue   color  fades   out  entirely.     The  amount  of  iodine  being 

known,  the  value  of  the  hyposulphite  solution  is  calculated  from 

standard-      the  reading  of  the  burette.     Now  measure  into  a  beaker  with  a 

izing  the 

iodide  so-    carefully  graduated  pipette   25   c.c.  of  the  hyposulphite  solution, 
.  dilute  to  300  c.c.,  add  a  few  drops  of  the  starch  solution,  and  drop, 
from  a  burette,  standard  iodine  solution  until  the  blue  color  is  per- 
manent.    The  value  of  the   hyposulphite  solution  being  known, 
that  of  the  iodine  solution  is  readily  calculated.     An  example  will 
illustration     illustrate  this  i     Suppose  we  find  by  titration   that   I   c.c.  of  our 

of  the  cal-  y 

cuiation  of  bichromate   solution    is   equal    to   .00566  gramme    metallic    iron ; 

of  the  so-    then,   as   the    reaction    is    6FeCl2 -j- K2Cr2O7 -f-  i4HCl  =  3Fe2Cl6-h 

2KCl  +  Cr2Cl6+7H2O,  I  equivalent  of  K2Cr2O7= 294.4  is  equal  to 

6  equivalents  of  Fe=336.     Hence  3 36 1294.4 =.005 66 1.00495 9,  or 
i  c.c.  of  the  bichromate  solution  contains  .004959  gramme  K2Cr2O7, 
and  consequently  25  c.c.  contain  .123975  gramme  K2Cr2O7.     Then, 
as  we   saw  by  the  formula  that  294.4  parts  bichromate  liberate 
761.1  parts  iodine,  we  have   294.4: 761.1=. 123975 :. 32051,  or  25 
c.c.  bichromate  solution  liberate  .32051  gramme  iodine.      We  now 
find  that  it  requires  25.3  c.c.  of  the  hyposulphite  solution  to  de- 
colorize the  solution  made  by  adding  25  c.c.  bichromate  solution 
to  the  iodide  of  potassium ;  consequently  each  c.c.  of  the  hyposul- 
phite contains   enough   NaHS2O3  to   react   with    .01267    gramme 
iodine.     We  now  measure  out    10  c.c.  of  the  hyposulphite  solu- 
tion, dilute  it  to  300  c.c.,  add  a  few  drops  of  starch  solution,  and 
find  that  it  requires   20.1  c.c.  of  the  iodide  solution  to  give  the 


ANALYSIS   OF  IRON  AND   STEEL.  63 

permanent  blue  color.  Hence  20.1  c.c.  =  .1267  gramme  iodine,  or 
i  c.c.  iodide  solution  contains  .006303  gramme  iodine.  As  the 
reaction  with  H2S  is  H2S-|-  2l  =  2HI-f  S,  it  requires  2  equivalents 
of  iodine  to  decompose  I  equivalent  of  H2S,  and  the  proportion  is 
2!  :  S  ::  253.7  :  32  ::  .006303  :  .000795,  or  I  c.c.  iodine  is  equal  to 
.000795  gramme  sulphur. 

The  standard  solutions  once  ready,  the  actual  determination  of 
sulphur  in  a  sample  is  very  simple.  Measure  50  c.c.  of  a  solution 
of  caustic  soda,  i.i  sp.  gr.,  free  from  sulphur,  into  the  first  of  the 
bottles  D.  The  second  need  not  be  used,  but  it  is  a  good  plan 
to  keep  a  caustic  potassa  solution  of  nitrate  of  lead  in  it,  and  Details  of 
attach  it  after  the  other,  to  be  certain  that  no  H2S  escapes  the  method, 
caustic  soda  solution.  Proceed  with  the  determination  as  directed 
on  page  53,  and  when  finished  wash  the  contents  of  the  bottle  D 
into  a  beaker,  dilute  to  500  c.c.,  acidulate  with  HC1,  add  a  few 
drops  of  starch  solution,  and  titrate  with  the  iodide  solution.  See 
exactly  how  much  HC1  is  required  to  acidulate  strongly  50  c.c. 
of  the  caustic  soda  solution,  and  this  amount  can  be  added  at 
once,  so  that  no  time  need  be  lost  in  testing  the  solution  with 
litmus  before  titrating. 


DETERMINATION    OF    SILICON. 

By  Solution  in  HNO3  and  HC1. 

Dissolve  5  grammes  of  drillings  in  40  c.c.  HNO3  with  the 
precautions  mentioned  on  page  58;  although  when  silicon  alone 
is  to  be  determined,  HNOo  of  1.2  sp.  gr.  may  be  used,  when,  in  Best  strength 

of  HNO8 

most  cases,  the  solution  of  the  drillings  will  be  more  rapid.  Re- 
move  the  cover,  evaporate  the  solution  to  dryness  in  the  air-bath, 
replace  the  cover,  and  raise  the  temperature  of  the  bath  until  the 
nitrate  of  iron  is  decomposed.  Remove  the  beaker  from  the  air- 
bath,  allow  it  to  cool,  add  30  c.c.  HC1,  and  heat  gradually  until 
all  the  ferric  oxide  is  dissolved.  Remove  the  cover,  and  evaporate 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Testing 
purity  of 
SiOo  with 
HF1. 


By  fusion 
with 
Na2C03 
and  evap- 
oration 
with  HC1. 


By  treating 
fusion  in 
crucible 
with 
H,S04. 


Drown's 
method  for 
pig-irons. 


again  to  dryness  in  the  air-bath,  redissolve  in  30  c.c.  HC1,  dilute 
to  about  150  c.c.,  and  filter  on  an  ashless  filter.  Detach  any 
adhering  silica  from  the  sides  and  bottom  of  the  beaker  with  a 
"  policeman,"  and  wash  it  out  with  cold  water.  Wash  the  filter 
first  with  dilute  HC1,  and  finally  with  water.  Dry,  and  ignite  in  a 
platinum  crucible  until  all  the  carbon  is  burned,  weigh  the  residue 
in  the  crucible,  moisten  it  with  water,  add  i— 10  drops  H2SO4, 
and  enough  HF1  to  dissolve  it  completely,  evaporate  to  dryness, 
ignite,  and  weigh.  The  difference  between  the  two  weights  is 
SiO2,  which  contains  46.67  per  cent,  of  Si.  In  the  absence  of 
HF1,  unless  the  SiO2  is  perfectly  white,  fuse  with  5  or  6  times  the 
weight  of  Na2CO3,  dissolve  in  water,  acidulate  with  HC1,  evapo- 
rate to  dryness  (in  a  platinum  or  porcelain  dish,  with  the  arrange- 
ment shown  on  page  15),  redissolve  in  HC1  and  water,  dilute, 
filter,  wash,  ignite,  and  weigh.  When  the  weight  of  Na2CO3 
taken  does  not  exceed  2  or  3  grammes,  allow  the  crucible  to  cool 
after  fusion,  and  then  add  to  it  gradually  an  excess  of  strong 
H2SO4,  heating  very  slowly,  until  the  mass  is  quite  liquid  and 
fumes  of  SO3  come  off  Allow  it  to  cool,  dissolve  in  water,  filter, 
wash  well,  ignite,  and  weigh. 

By  Solution  in  HNO3  and  H2SO4. 

Drown  *  has  suggested  a  method  which,  for  pig-irons,  has  come 
into  very  general  use,  and  which  is  much  more  rapid  than  the 
other  method,  and  quite  as  exact.  Treat  I  gramme  of  borings  in  a 
platinum  or  porcelain  dish  with  20  c.c.  HNO3,  1.2  sp.  gr.  When 
all  action  has  ceased,  add  20  c.c.  of  H2SO4  (equal  parts  acid  and 
water),  and  evaporate — using  the  arrangement  shown  on  page  1 5 — 
until  copious  fumes  of  SO3  are  given  off.  Allow  to  cool,  and 
dilute  with  150  c.c.  water;  heat  carefully  until  all  the  sulphate  of 
iron  has  dissolved,  filter  hot,  wash  first  with  dilute  HC1,  i.i  sp.  gr., 
and  then  with  hot  water,  ignite,  and  weigh.  Treat  the  contents 


*  Jour.  Inst.  Min.  Engineers,  vii.  346. 


ANAL  YSIS   OF  IRON  AND   STEEL.  65 

of  the  crucible  with  H2SO4  and  HF1,  evaporate  to  dryness,  ignite, 
and  weigh  again.     The  difference  between  the  two  weights  is  SiO2. 

By  Volatilization  in  a  Current  of  Chlorine  Gas. 

As  almost  all  steels  and  irons  contain  slags  of  various  com-   presence  of 
positions,  it  must  be  understood  that  the  SiO2  obtained  by  the     jJonand 
methods  above  given  is  the  total  SiO2,  comprising  any  SiO2  that     steel 
may  be  present  in  the  admixed  slag,  as  well  as  that  formed  from 
the  Si  present  in  the  metal.     The  volatilization  method  separates  separation 
the  two.     The  process    suggested  by  Drown,*   and  worked  out     siO2. 
independently  two  years  later  by  Watts,f  is  as  follows :    Fig.  47   Description 
shows  the  general  arrangement  of  the  apparatus.     The  large  flask     °^** 
contains  binoxide  of  manganese  in  lumps.     The  bottle  above  it 
contains  strong  common  HC1,  which  runs  into  the  flask  through 
a  siphon-tube  extending  almost  to  the  bottom.     The  flask  stands 
in  a  dish   containing  water,  which  can  be  heated  by  the  burner 
under  the  tripod.     The  evolution-tube  from  the  flask  has  a  stop- 
cock, and  connects  with  the  three  bulb-tubes  on  the  stand,  the 
first   containing  water,  the   second   pumice-stone,   and   the   third 
pumice  saturated  with  strong  H2SO4.     The  outlet-tube  from  the 
latter  leads  into  the  porcelain  or  glass  tube  in  the  furnace.     This  Purification 
tube  contains  small  lumps  of  charcoal  or  gas  carbon,  kept  in  posi-     from  o. 
tion  by  loosely-fitting  plugs  of  asbestos,  and  occupying  about  8 
inches  (200  mm.)  in  the  middle  of  the  tube.     The  outlet-tube  from 
this  connects  with  the  drying-tubes  on  the  second  stand,  which 
contain  pumice  moistened  with  strong   H2SO4.     The  outlet  from 
the  second  drying-tube  connects  with  the  glass  combustion-tube, 
which  leads  through  the  second  furnace,  and  is  bent  at  a  right 
angle  where  it  is  connected^wjth  the  large  tubes,  half  filled  with 
water.     The  apparatus  being  in   order,  J  start  a  slow  current  of 

*  Jour.  Inst.  Min.  Engineers,  viii.  508.  f  Chem.  News,  xlv.  279. 

J  All  the  stoppers  used  should  be  of  rubber,  coated  with  paraffine  on  the  ends,  or 
of  asbestos,  and  where  glass  tubes  are  joined  together  with  rubber  the  ends  of  the 
glass  tubes  should  be  brought  into  close  contact. 


66 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


ANALYSIS   OF  IRON  AND   STEEL. 


67 


chlorine  through  the  apparatus  by  blowing  HC1  from  the  bottle  Details  of 
into  the  flask  and  filling  the  dish  in  which  the  latter  stands  with  method. 
water.  Light  a  low  light  under  the  dish,  and  open  the  stopcock 
wide  enough  to  allow  a  very  slow  current  to  bubble  through  the 
bulbs.  Light  the  burners  of  the  first  furnace  so  that  the  tube  is 
heated  to  dull  redness.  When  the  apparatus  is  all  full  of  chlorine, 
weigh  i  gramme  of  pig-iron,  or  3  grammes  of  steel,  into  a  porce- 
lain boat  about  3  inches  long,  distributing  the  drillings  evenly 
along  the  bottom  of  the  boat.  Remove  the  stopper  at  the  rear 
end  of  the  second  tube  and  insert  the  boat  to  about  the  centre. 
Replace  the  stopper,  and  continue  the  current  of  chlorine  in  the 
cold  for  ten  or  fifteen  minutes  to  make  sure  that  no  oxygen 
remains  in  the  tube,  then  light  the  burner  under  the  forward  end 
of  the  boat.  The  heat  must  be  just  sufficient  to  volatilize  the 


ferric  chloride,  which  should  condense  in  the  cooler  part  of  the  Fe2ci<5. 
tube,  and  the  current  of  gas  should  be  slow  enough  to  prevent 
any  ferric  chloride  from  being  carried  forward  into  the  water-tubes 
or  any  loss  of  carbon  from  the  boat.  When  the  fumes  of  ferric 
chloride  begin  to  come  off  more  slowly,  light  the  next  burner,  and 
continue  until  all  the  burners  under  the  boat  are  lighted,  main- 
taining the  heat  until  the  fumes  of  ferric  chloride  cease.  The  tube 
for  the  entire  length  occupied  by  the  boat  should  be  at  a  dull  red 
heat.  Should  the  condensed  ferric  chloride  at  any  time  choke 
the  tube  so  as  to  prevent  the  passage  of  the  gas,  heat  that  part 
of  the  tube  gently  with  a  spirit-lamp,  so  as  to  drive  the  ferric 
chloride  a  little  farther  along  the  tube.  When  the  fumes  of  ferric 
chloride  are  no  longer  given  off  from  the  boat,  the  operation  may 
be  considered  finished.  Turn  out  the  lights  under  the  tube  con- 
taining the  boat,  remove  the  stopper,  and  draw  out  the  boat, 
which  now  contains  the  carbon,  the  slag,  and  the  greater  part  of 
the  manganese  (as  MnCl2)  which  were  contained  in  the  iron  or  Residue  in 
steel.  This  residue  may  be  used  for  the  determination  of  the 
carbon  or  the  slag,  as  will  be  shown  farther  on.  If  another 
determination  is  to  be  made,  another  tube  may  be  substituted  for  or  sla«- 


68  THE    CHEMICAL   ANALYSIS   OF  IRON. 

the  one  which  contained  the  boat,  and  the  analysis  carried  out 
in  the  manner  described  above.  If  not,  put  out  all  the  lights, 
close  the  stopcock,  and  withdraw  the  combustion-tube  with  the 
water-tubes.  Remove  the  stoppers  from  the  latter,  and  pour  the 
contents  of  these  tubes  into  a  platinum  dish  containing  a  small 
amount  of  an  aqueous  solution  of  sulphurous  acid,  to  prevent  the 
chlorine  in  the  solutions  from  acting  on  the  platinum.  Rinse  the 
tubes  into  the  dish,  and  if  any  silica  has  separated  out  and  adheres 
to  the  water-tubes  or  to  the  end  of  the  combustion-tube,  loosen 
it  with  a  "policeman"  and  wash  it  into  the  dish.  Add  5  c.c.  strong 
H2SO4,  evaporate  to  dryness,  and  heat  until  fumes  of  SO3  are 
given  off.  Allow  the  dish  to  cool,  add  100  c.c.  cold  water,  and 
filter  off  on  a  small  ashless  filter  any  SiO2,  which  burn  and  weigh 
Separation  as  such.  Calculate  to  Si.  The  filtrate  from  the  SiO2  will  contain 
2'  any  TiO2  which  may  have  been  in  the  metal  and  which  can  be 


determined,  as  will  be  shown   farther   on.      Silicon  and  titanium 

tion  of 

Sici4and     are  volatilized  as  chlorides,  SiCL  and  TiCL,  under  the  conditions 

TiCl4,  de- 

composi-     shown  above,  and   decomposed  by  water  thus:    SiCl4+  2H2O  = 

tion  by 

H2o.         4HCl  +  TiO2  and  TiCl4-f  2H2O=4HCl  +  TiO2. 

Rapid   Method   for   Determination   of    Silicon.      (S.    Alfred 

Ford.*) 

At  the  Edgar  Thomson  Steel-Works  the  molten  pig-metal  is 

taken  directly  from  the  furnaces  to  the  converters,  and  it  is  gener- 

ally necessary  to  determine  the  amount  of  silicon  in  the  pig-iron 

Method  of     as  a  guide  in  blowing  the  metal.     To  get  the  sample  for  analysis,  a 

taking 

sample.      small  ladle  is  dipped  into  the  iron  as  it  runs  from  the  furnace,  and 

a  small  quantity  of  molten  iron  is  taken.     The  ladle  is  then  held 

about  three  feet  above  a  bucket  of  water,  and  the  molten  metal 

Appearance    dropped  into  the  water,  at  the  same  time  giving  the  ladle  a  circular 

pending      motion    over   the  bucket.      This   will   cause  the  iron  to  form  in 

of  SL         globules,  more  or  less  round  according  to  the  amount  of  silicon 


*  Prepared  by  Mr.  Ford  for  this  volume. 


ANALYSIS   OF  IRON  AND   STEEL.  fa 

contained  in  the  iron.  Thus,  with  iron  which  contains  2  per  cent, 
of  silicon  or  more,  the  globules  will  be  almost  perfectly  round, 
concave  on  the  upper  surface,  and  generally  from  ^  inch  (6  mm.) 
to  }£  inch  (9  mm.)  in  diameter ;  while  if  the  iron  be  low  in  sili- 
con, the  shot  or  drops  will  be  very  small,  flat,  and  irregular  in 
shape,  and  if  the  iron  be  very  low  in  silicon,  as  is  the  case  with 
Spiegel  and  ferromanganese,  the  shot  will  be  elongated  and  have 
tails  sometimes  J^  inch  (6  mm.)  in  length.  In  fact,  a  close  ob- 
server can  soon  judge  very  closely  as  to  the  amount  of  silicon 
from  the  condition  of  these  shot  or  drops.  The  next  step  in  the 
process  is  to  take  the  shot  from  the  bucket  and  place  them  for  a 
minute  in  the  ladle  which  has  been  used  to  dip  up  the  molten  iron. 
The  ladle,  being  hot,  will  dry  the  shot  almost  instantly.  The  shot  Powdering 
are  then  placed  in  a  large  steel  mortar  (Fig.  5,  page  12)  and  p\l^ 
crushed.  The  crushed  shot  are  then  sifted  with  a  fine  sieve,  and 
.5  gramme  of  the  fine  siftings  are  placed  in  a  platinum  evapo-  Determina- 
rating-dish,  10  c.c.  HC1,  1.2  sp.  gr.,  are  then  added,  and  the  dish  sT 
covered  with  a  watch-glass.  The  dish  is  then  placed  over  a  light, 
and  the  iron  dissolved;  as  soon  as  solution  takes  place,  which 
requires  about  one  minute,  as  the  particles  of  iron  are  so  small, 
the  watch-glass  is  removed  and  the  solution  evaporated  to  dryness 
as  rapidly  as  possible  over  a  naked  light ;  as  soon  as  dry,  not  even 
waiting  for  the  dish  to  cool,  dilute  HC1  is  dropped  on  the  chloride 
of  iron,  and  as  soon  as  all  the  sesquioxide  of  iron  (which  may  have 
been  formed  by  the  decomposition  of  the  chloride)  is  dissolved, 
water  is  added.  The  contents  of  the  dish  are  then  poured  on  a 
filter,  to  which  is  attached  a  pump,  filtered,  and  washed.  The 
filter  and  its  contents  are  then  placed  in  a  weighed  platinum 
crucible,  placed  over  a  blast-lamp;  as  soon  as  the  filter-paper  is  Burning c in 

stream  of 

burned  off,  the  crucible  is  turned  on  its  side,  the  lid  removed,  and     o. 
a  small  jet  of  oxygen  is  driven  very  gently  into  the  crucible.     As 
soon  as  what  little  carbon  there  is  in  the  precipitate  is  burned  off, 
the  crucible  is  cooled  and  weighed,  and  the  amount  of  silicon  cal- 
culated from  the  weight  of  the  silica  in  the  crucible. 


70  THE    CHEMICAL   ANALYSIS   OF  IRON. 

Time  re-  By  this   method  the  amount  of  silicon  in  a  pig-iron  can  be 

quired  for 

determined  in  twelve  minutes  from  the  time  the  ladle  is  put  into 


"f  s°n        the  molten   iron,  and  it  gives  results  close  enough  for  practical 
purposes. 


DETERMINATION    OF    SLAG   AND    OXIDES. 

Presence  of          A  certain  amount  of  slag  and  oxide  of  iron  is  always  present  in 

slag  in  iron 

and  steel,  puddled  iron  as  a  mechanical  admixture.  It  is  also  found,  as  a 
general  thing,  in  basic  steel,  and  the  presence  of  slag  in  steel  made 
by  the  acid  process,  as  well  as  in  pig-iron,  is  not  unusual.  The 
easiest  method  for  the  determination  of  these  substances  is  by 
solution  in  iodine,  as  suggested  by  Eggertz. 

By  Solution  in  Iodine. 

Details  of  Weigh  5  grammes  of  borings  free  from  lumps  into  a  No.  2 

method.  Griffin's  beaker.  Stand  the  beaker,  carefully  covered  with  a  watch- 
glass,  in  a  dish  filled  with  scraped  ice  or  snow,  so  that  the  bottom 
and  sides  of  the  beaker  half-way  up  shall  be  in  contact  with  it. 
Pour  over  the  iron  in  the  beaker  25  c.c.  of  ice-cold  boiled  water, 
and  stir  until  all  the  air  in  the  borings  has  escaped.  Add  grad- 
ually 28  or  30  grammes  of  resublimed  iodine,*  stirring  occasion- 
ally, until  all  the  iodine  has  dissolved.  Keep  the  beaker  con- 
stantly surrounded  by  ice,  and  add  the  iodine  slowly  enough  to 
prevent  any  rise  in  the  temperature  of  the  solution.  Stir  the  solu- 
tion frequently  until  the  iron  is  perfectly  dissolved,  which  will 
take  several  hours;  then  add  100  c.c.  cold  boiled  water,  allow  the 
insoluble  matter  to  settle,  and  decant  the  supernatant  fluid  on  a 
small  ashless  filter.  Wash  the  insoluble  matter  several  times,  by 

insuring  decantation,  with  cold  water,  then  add  to  it  a  little  water,  with  a 
.  few  drops  of  HC1,  and  observe  whether  any  hydrogen  is  disen- 
gaged. If  none  can  be  perceived,  the  metallic  iron  may  be  con- 
sidered entirely  dissolved ;  but  if  gas  is  given  off,  the  opposite  is 


*  Page  34. 


ANALYSIS   OF  IRON  AND   STEEL,  jl 

the  case.  In  either  event,  quickly  decant  the  acidulated  water  on 
the  filter,  and  if  any  metallic  iron  remains,  add  a  very  little  water 
and  some  iodine  to  dissolve  the  iron  entirely.  Then  transfer  the 
insoluble  matter,  consisting  of  graphite,  carbonaceous  matter,  slag,  Separation 
oxide  of  iron,  and  some  silica,  to  the  filter,  wash  the  filter  once 
with  very  dilute  HC1  (i  acid  to  20  water),  and  finally  with  cold 
water,  until  the  filtrate  is  free  from  iron.  Unfold  the  filter,  and 
with  a  fine  jet  wash  the  insoluble  matter  off  into  a  small  platinum 
or  silver  dish.  Evaporate  almost  to  dryness,  add  50  c.c.  solution 

of  caustic  potassa,  sp.  gr.   i.i,  and  boil  5  or  10  minutes.     Decant 

i\.    *-<, ' 

the  liquid  on  a  very  small,  ashless  filter,  repeat  the  boiling  with 
fresh,  caustic  potassa,  transfer  the  insoluble  matter  to  the  filter,  and 
wash  well  with  hot  water.  Wash  once  with  dilute  HC1  (i  acid  to 
20  water),  and  finally  with  hot  water,  until  the  filtrate  gives  no 
precipitate  with  a  solution  of  nitrate  of  silver.  Dry,  ignite,  and 
weigh  as  Slag  and  Oxide  of  Iron. 

Instead  of  using  iodine  directly  for  the  solution  of  the  iron,  a 
solution  of  iodine  in  iodide  of  iron,  as  suggested  by  Eggertz,*  use  of  iodine 
may  be  used  to  great  advantage,  as  it  affords  a  ready  method 
for  getting  rid  of  the  impurities  usually  present  in  resublimed 
iodine.  Treat  5  grammes  of  iron  (as  free  as  possible  from  silicon) 
with  25  grammes  of  iodine,  and,  when  solution  is  complete,  add 
30  grammes  more  of  iodine,  which  will  dissolve  in  the  iodide  of 
iron  in  a  few  minutes.  Dilute  to  50  c.c.  with  cold  boiled  water 
and  filter  through  a  washed  filter.  Add  the  filtrate  at  once  to  5 
grammes  of  the  weighed  sample,  and,  after  solution  is  complete, 
proceed  as  directed  above. 

By  Volatilization  in  a  Current  of  Chlorine  Gas. 

Proceed  exactly  as  in  the  method  for  the  determination  of  sili- 
con (pages  65  et  seq^)  until  the  boat  is  withdrawn  from  the  com- 
bustion-tube. Wash  the  contents  of  the  boat  into  a  small  beaker 

*  Jern-Kontorets  Annaler,  1881,  p.  301,  and  Chem.  News,  xliv.  173. 


iron  as  a 
solvent. 


72  THE    CHEMICAL   ANALYSIS   OF  IRON. 

washing  out  with  a  jet  of  cold  water,  and  filter  on  a  small  ashless  filter.     The 

soluble 

chlorides,    water  dissolves  any  soluble  metallic   chlorides,  MnCl2,CaCl2,  etc., 

which  are  not  volatile  at  a  low  red  heat,  and  the  insoluble  matter 

in  the  filter  consists  of  slag  and  carbon.     Burn  off  the  carbon  and 

weigh  the  residue  as  Slag  and  Oxides.     Or,  if  the  carbon  has  been 

Using  coun-  determined  by  another  operation,   filter  the  carbon   and   slag   on 

terpoised 

filters.  a  counterpoised  filter*  or  on  a  Gooch  crucible,  dry  at  100°  C.,  and 
weigh  as  Carbon,  Slag,  and  Oxides ;  by  subtracting  the  weight  of 
the  carbon  the  difference  is  Slag  and  Oxides. 


DETERMINATION    OF    PHOSPHORUS. 

For  the   determination   of  phosphorus   in   iron   and   steel  but 

two  methods  are  in  general  use,  either  of  which,  properly  carried 

out,  will   give  extremely  accurate  results.     Some  chemists  prefer 

one  method,  some  the  other,  while  a  combination  of  the  two  is 

sometimes   used.     The  two   general   methods   are  known  respec- 

Methodsin     tively  as  the  Acetate  Method  and  the  Molybdate  Method.     There 

use.  are  innumerable  variations  in  the  details,  especially  of  the  latter 

method,   but    any    departure    from   what    might    be    termed    the 

standard  instructions  should  never  be  attempted  by  any  but  a  very 

experienced  analyst. 

The  Acetate  Method. 

The  essential  parts   of  this  method  were  suggested  by  Fre- 
senius,f  the  changes  and  improvements  in  details  being  the  work 
of  many  chemists.  J 
Details  of  Dissolve  5  grammes  of  drillings  in  a  No.  4  Griffin's  beaker  in 

the  acetate 

method.      40  c.c.  strong  HNO3,  with  the  precautions  detailed  on  page  58. 
Evaporate  the   solution  to   dryness    in   the   air-bath,   replace   the 

*  See  page  22.  f  Jour,  fur  Pr.  Ch.,  xlv.  258. 

J  Tenth  Census  of  the  U.  S.,  vol.  xv.     "  Iron  Ores  of  the  U.  S.,"  p.  523. 


ANALYSIS   OF  IRON  AND   STEEL.  73 

cover,  and  heat  until  the  nitrate  of  iron  is  nearly  all  decomposed. 
Cool,  add  30  c.c.  HC1,  heat  gradually  until  the  oxide  of  iron  is 
dissolved,  and  evaporate  to  dryness  again  in  the  air-bath.     Cool, 
dissolve  in  30  c.c.  HC1,  dilute,  and,  in  steels  or  puddled  iron,  when  when  si  is 
silicon  is  to  be  determined,  filter,  and  treat  the  insoluble  matter  as     termined. 
directed  for  the  determination  of  Si,  page  64. 

In  the  case  of  pig-irons  which  may  contain  titanium,  filter,  and 
keep  the  residue  of  graphite,  silica,  etc.,  for  treatment,  as  directed  when  Ti  is 
farther  on,  "  when  titanium  is  present." 

In  the  case  of  steels,  when  silicon  is  not  to  be  determined  in  when  si  is 

not  to  be 

this  portion,  the  solution  need  not  be  filtered  at  all,  but  may  be     deter- 
diluted  at  once  to  about  250  c.c. 

In  any  case,  heat  the  filtered  or  unfiltered  HC1  solution  nearly 
to  boiling,  remove  the  beaker  from  the  light,  and  add  gradually 
from  a  small  beaker  a  mixture  of  10  c.c.  NH4HSO3*  and  20  c.c. 
NH4HO,  stirring  constantly.  The  precipitate,  which  forms  at 
first,  redissolves,  and  when  all  but  about  2  or  3  c.c.  of  the 
NH4HSO3  solution  has  been  added,  replace  the  beaker  over  the 
light.  If  at  any  time  while  adding  the  NH4HSO3  solution  the  Deoxidiz- 

ing  the 

precipitate  formed  will  not  redissolve  even  after  vigorous  stirring,  solution. 
add  a  few  drops  of  HC1,  and,  when  the  solution  clears,  continue 
the  addition,  very  slowly,  of  the  NH4HSO3.  After  replacing  the 
beaker  on  the  light,  add  to  the  solution  (which  should  smell  quite 
strongly  of  SO2)  NH4HO,  drop  by  drop,  until  the  solution  is  quite 
decolorized,  and  until  finally  a  slight  greenish  precipitate  remains 
undissolved  even  after  vigorous  stirring.  Now  add  the  remaining 
2  or  3  c.c.  of  the  NH4HSO3  solution,  which  should  throw  down  a 
white  precipitate,  which  usually  redissolves,  leaving  the  solution 
quite  clear  and  almost  perfectly  decolorized.  Should  any  precipi- 
tate remain  undissolved,  however,  add  HC1,  drop  by  drop,  until 
the  solution  clears,  when  it  should  smell  perceptibly  of  SO2.  If 
the  reagents  are  used  in  exactly  the  proportions  indicated,  the 


*  See  page  37. 
6 


74  THE    CHEMICAL   ANALYSIS   OF  IRON. 

reactions  will  take  place  as  described,  and  the  operations  will  be 
readily  and  quickly  carried  out.  If  the  solution  of  NH4HSO3 
is  weaker  than  it  should  be,  of  course  the  ferric  chloride  will  not 
be  reduced,  and  the  solution,  at  the  end  of  the  operation  described 
above,  will  not  be  decolorized  and  will  not  smell  of  SO2.  In  this 
case  add  more  of  the  NH4HSO3  (without  the  addition  of  NH4HO) 
until  the  solution  smells  strongly  of  SO2,  then  add  NH4HO  until 
the  slight  permanent  precipitate  appears,  and  redissolve  it  in 
as  few  drops  of  HC1  as  possible.  The  solution  being  now  very 
nearly  neutral,  the  iron  in  the  ferrous  condition,  and  an  excess  of 
SO2  being  present,  add  to  the  solution  5  c.c.  of  HC1  to  make  it 
decidedly  acid  and  to  insure  the  complete  decomposition  of  any 

Boning  off      excess  of  the  NH4HSO3  which  may  be  present.     Boil  the  solu- 

soo.          tion,*  while  a  stream  of  CO2  passes  through  it,  until  every  trace 

of  SO2  is   expelled,  then  pass   a  current  of   H2S  through  it  for 

Precipitating  about  fifteen  minutes  to  precipitate  any  arsenic  which  may  be 
present,  and  finally  allow  the  solution  to  stand  in  a  warm  place 
until  the  smell  of  H2S  has  disappeared,  or,  better,  pass  a  current 
of  CO2  through  the  solution,  which  will  expel  the  H2S  in  a  few 
minutes.  The  arrangement,  Fig.  48,  is  convenient  for  this  pur- 
pose. Filter  from  any  As2S3,  CuS,  S,  etc.,  into  a  No.  5  beaker, 
wash  with  hot  water,  and  to  the  filtrate  add  a  few  drops  of  bro- 
mine-water, and  cool  it  by  placing  the  beaker  in  cold  water.  To 
the  cold  solution  add  NH4HO  from  a  small  beaker  very  slowly, 
and  finally  drop  by  drop,  with  constant  stirring.  The  green  pre- 
cipitate  of  ferrous  hydrate  which  forms  at  first  is  dissolved  by 


phosphate   stirring,    leaving   the   solution   perfectly   clear,   but   subsequently, 

dratehy       although  the   green  precipitate   dissolves,  a  whitish  one  remains, 

and  the  next  drop  of  NH4HO  increases  the  whitish  precipitate  or 

gives  it  a  reddish  tint,  and  finally  the  greenish  precipitate  remains 

undissolved    even   after   vigorous    stirring,    and    another   drop    of 


*  By  passing  a  current  of  CO2  through  the  boiling  solution  the  SO2  is  soon  ex- 
pelled, and  the  operation  requires  no  watching. 


ANALYSES   OF  IRON  AND  STEEL. 

NH4HO  makes  the  whole  precipitate  appear  green.  If  before  this 
occurs  the  precipitate  does  not  appear  decidedly  red  in  color,  dis- 
solve the  green  precipitate  by  a  drop  or  two  of  HC1,  and  add  a 
little  bromine-water  (i  or  2  c.c.),  then  add  NH4HO  as  before,  and 
repeat  this  until  the  reddish  precipitate  is  obtained,  and  then  the 

FIG.  48. 


75 


green  coloration  as  described  above.  Dissolve  this  green  precipi- 
tate in  a  very  few  drops  of  acetic  acid  (sp.  gr.  1.04),  when  the  pre- 
cipitate remaining  will  be  quite  red  in  color,  then  add  about  I  c.c. 
of  acetic  acid,  and  dilute  the  solution  with  boiling  water,  so  that 
the  beaker  may  be  about  four-fifths  full.  Heat  to  boiling,  and  when 


76 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Filtering  and  the  solution  has  boiled  one  minute,  lower  the  light,  filter  as  rapidly 

washing 

thepre-  as  possible  through  a  5^-inch  (i4O-mm.)  filter,  and  wash  once 
with  hot  water.  The  filtrate  should  run  through  clear,  but  in  a 
few  minutes  it  will  appear  cloudy  by  the  precipitation  of  the  ferric 
oxide,  which  has  been  formed  by  the  exposure  of  the  filtered  solu- 

Precautions.  tion  to  the  air.  The  points  to  be  observed  are  the  red  color  of  the 
precipitate  and  the  clearness  of  the  solution  when  it  first  runs 
through.  Ferric  phosphate  being  white,  the  red  color  of  the  precipi- 
tate shows  that  enough  ferric  salt  was  present  in  the  solution  to  form 
ferric  phosphate  with  all  the  phosphoric  acid,  and  enough  more  to 
color  the  ferric  phosphate  red  with  the  excess  of  ferric  oxide. 

When  the  precipitate  has  drained  quite  dry,  pour  about  1 5  c.c. 
of   HC1  into  the   beaker  in   which    the  precipitation  was    made, 

Solution  of     warm  it  slightly  so  that  the  acid  may  condense  on  the  sides  and 

the  precip- 
itate,         dissolve  any  adhering  oxide,  wash  off  the  cover  into  the  beaker, 

add  about  10  c.c.  of  bromine-water,  pour  this  on  the  filter  con- 
taining the  precipitate,  allowing  it  to  run  around  the  edge  of  the 
filter,  and  let  the  solution  run  into  a  No.  I  Griffin's  beaker.  Wash 
out  the  beaker  once  or  twice,  and  then  wash  the  filter  well  with 
hot  water.  If  the  acid  in  the  beaker  is  not  sufficient  to  dissolve 
the  precipitate  completely,  drop  a  little  strong  acid  around  the 

Cause  of  edge  of  the  filter  before  washing  it  with  hot  water.  The  scaly 
cuitiy  sol-  film  of  difficultly  soluble  oxide  which  sometimes  forms  on  boiling 
the  acetate  precipitate  is  caused  by  the  presence  of  too  much 
acetate  of  ammonium,  but  when  the  instructions  given  above  are 
carefully  carried  out  it  never  appears.  Evaporate  the  solution  in 
the  small  beaker  nearly  to  dryness  to  get  rid  of  the  excess  of 
HC1,  add  to  it  a  filtered  solution  of  5  or  10  grammes  of  citric  acid 
(according  to  the  size  _of  the  precipitate  of  Fe2O3,  etc.)  dissolved  in 
10  to  20  c.c.  of  water,  then  5  to  10  c.c.  of  magnesia-mixture  and 
enough  NH4HO  to  make  the  solution  faintly  alkaline.  Stand  the 

Predpita-      beaker    in  cold  water,  and  when    the  solution  is  perfectly  cold, 

tion  of  * 

theMg2      add  to  it  one-half  its  volume  of  strong  NH4HO  and  stir  it  well. 

(NH4)2 

P2o8.         When  the  precipitate  of  Mg2(NH4)2P2O8  has  begun  to  form,  stop 


ANALYSIS   OF  IRON  AND   STEEL.  j>j 

stirring,  and  allow  it  to  stand  in  cold  water  for  ten  or  fifteen 
minutes,  then  stir  vigorously  several  times  at  intervals  of  a  few 
minutes,  and  allow  it  to  stand  overnight.  Filter  on  a  small  ash- 
less  filter,  and  wash  with  a  mixture  of  2  parts  of  water  and  I  part 
of  NH4HO  containing  2.5  grammes  of  NH4NO3  to  100  c.c. 

Dry  the  filter  and  precipitate,  and  ignite  them  at  a  very  low  Filtering  and 
temperature  at  first  so  as  to  carbonize  the  filter  without  decom-  th™recip- 
posing  the  precipitate,  which  may  then  be  readily  broken  up  with 
a  platinum  wire.  Raise  the  heat  gradually,  and  finally  ignite  at 
the  highest  temperature  of  the  Bunsen  burner.  When  the  precipi- 
tate is  perfectly  white,  cool  and  weigh.  Then  fill  the  crucible  half 
full  of  hot  water,  add  from  5  to  20  drops  of  HC1,  and  heat  until 
the  precipitate  has  dissolved.  Filter  off  on  another  small,  ashless 
filter  any  little  SiO2  or  Fe2O3  that  may  remain,  ignite,  and  weigh. 
The  difference  between  the  two  weights  is  the  weight  of  Mg2P2O7, 
which,  multiplied  by  0.2793,  gives  the  weight  of  P. 

When  Titanium  is  Present. 

When  a  solution  of  ferric  chloride  containing  TiO2  and  P2O5  is 
evaporated  to  dryness,  a  compound  of  TiO2,P2O5  and  Fe2O3  is 
formed,  completely -insoluble  in  dilute  HCL* 

Iron  ores  and  pig-irons  containing  TiO2  require,  therefore,  a 
somewhat  different  method  of  treatment  from  that  given  above. 

Dry  and  ignite  the  residue  of  graphite,  silica,  etc.,  from  the 
solution  of  the  pig-iron,  so  as  to  burn  off  all  the  carbon.     Moisten  Treatment 
this  residue  with  cold  water,  add  5   to   10  drops  of  H2SO4  and     soiubie 
enough   HF1  to  dissolve  the  silica,  and  evaporate  until  fumes  of 
SO3  are  given    off.     While  this  is  going    on,  proceed  with    the 
deoxidation  of  the  filtrate  as  described  above,  but  when  the  SO2 
has  been  driven  off  do  not  pass  H2S  through  the  solution,  but 
cool  it,  and  proceed  with   the  acetate  precipitation.      Instead  of  Treatment  of 

the  precip- 

dissolving  the  precipitate,  after  washing  it  as  described  above,  dry     hate  of  fer- 

*  Published  in  Report  on  Methods  employed  in  the  Analysis  of  the  "  Iron  Ores," 
Tenth  Census  U.S.,  vol.  xv.  p.  512.  I  first  noted  this  fact  in  1878. 


7  8  THE    CHEMICAL   ANALYSIS   OF  IRON. 

ricphos-  the  filter  and  precipitate  in  the  funnel,  being  careful  not  to  heat 
it  so  as  to  scorch  the  filter.  Clean  out  any  of  the  precipitate 
which  may  have  adhered  to  the  sides  of  the  beaker  in  which  the 
precipitation  was  made,  by  wiping  it  with  filter-paper,  and  dry 
this  paper  with  the  filter  and  precipitate. 

When  the  precipitate  is  quite  dry,  transfer  it  to  a  small  por- 
celain mortar.  The  precipitate  may  be  readily  detached  from  the 
filter  by  rubbing  the  sides  of  the  latter  together  over  a  large  piece 
of  white,  glazed  paper,  so  that  any  little  particles  that  fall  out 
may  be  seen.  Roll  up  the  filter  with  the  bits  of  paper  which 
were  used  to  wipe  out  the  beaker,  wrap  a  piece  of  platinum  wire 
around  it,  burn  it  on  the  lid  of  the  crucible  in  which  the  graphitic 
Fusion  of  the  residue  was  treated,  and  transfer  the  ash  to  the  mortar.  Grind 

precipi- 

tate.  the  precipitate  and  ash  with  3  to  5  grammes  of  Na2CO3  and  a 
little  NaNO3,  and  transfer  it  to  the  crucible  containing  the  residue 
which  was  treated  by  HF1  and  H2SO4.  Clean  the  mortar  and 
pestle  by  grinding  a  little  more  Na2CO3,  and  add  this  to  the  other 
portion  in  the  crucible.  Fuse  the  whole  for  half  an  hour  or  more, 
cool,  dissolve  the  fused  mass  in  hot  water,  filter  from  the  insoluble 
Fe2O3,  etc.,*  acidulate  the  filtrate  with  HC1,  add  a  few  drops  of 
NH4HSO3,  boil  off  all  smell  of  SO2,  and  pass  H2S  through  the 
hot  solution  to  precipitate  any  arsenic  that  may  be  present.  Pass 
Precipitation  a  current  of  CO9  through  the  solution  to  expel  the  excess  of  H,S, 

of  the  As. 

filter  off  the  As2S3,  and  to  the  filtrate  add  a  sufficient  amount  of 
Fe2Cl6  solution  to  combine  with  all  the  P2O5  as  Fe2(PO4)3  and  leave 
a  slight  excess.  Add  a  slight  excess  of  NH4HO,  which  should 
throw  down  a  red  precipitate,  while  the  solution  is  alkaline  to  test- 
paper  ;  then  add  acetic  acid  to  slightly  acid  reaction,  boil,  and  filter 
Precipitation  off  the  Fe2(PO4)3  and  Fe2O3,  and  wash  with  hot  water.  Dissolve 
Si  the  precipitate  in  HC1,  allow  the  solution  to  run  into  a  small 


P2°8'         beaker,  evaporate  until  the  solution  is  syrupy,  add  citric  acid  and 


*  This  Fe2O3,  etc.,  contains  all  the  titanium  that  was  in  the  pig-iron  as  titanate  of 
soda,  and  must  be  kept  for  the  estimation  of  that  element  when  it  is  to  be  determined. 


ANAL  YSIS   OF  IRON  AND   STEEL.  yg 

magnesia-mixture,  and  precipitate  the  Mg2(NH4)2P2O8  as  described 

above.     Unless  the  amount  of  phosphorus  is  very  small,  a  second 

fusion  of  the  insoluble  residue  of  Fe2O3,  etc.,  is  necessary.     The  two  Necessity  for 

filtrates  can  then  be  added  together,  acidulated  with  HC1,  and  the 

remainder  of  the  process  carried  out  as  directed  above.     To  avoid 

the  fusion  of  the  acetate  precipitate  with  Na2CO3,  which  is  always 

troublesome,  the    method   for   the    determination   of  phosphorus 

may  be  modified  (in   many  cases  with   advantage,  and   generally 

when  titanium  is  not  to  be  estimated)  as  follows  :   After  filtering 

off  the  insoluble  matter,   graphite,  silica,  etc.,  ignite  it,  burn  off 

the  graphite,  and  treat  the  residue  with  HF1  and  H2SO4,  evapo- 

rate down  until  the  excess  of  H2SO4  is  driven  off,  and  fuse  with 

Na2CO3.     Treat  the  fused  mass  with  water,  and  filter.     Acidulate 

the  filtrate  with   HC1,  and    add  it  to    the   main    solution,  which 

has  been  deoxidized  in  the  mean  time  with  bisulphite  of  ammo-  Method 

nium.     Expel  the  last  traces  of  SO2  from  the  united  filtrates  by 

boiling  and  passing  a  current  of  CO2  through  the  solution,  as 

previously   directed.      If   the    solution    remains    clear,   pass    H9S 

through    it,  and   filter  off  the  precipitated  sulphides.      Cool  the 

solution,  and  make  the  acetate  precipitation  as  directed  on  page 

74.     The  only  danger  to  be  apprehended  now  is  the  tendency  of  Tendency  of 

titanic  acid  to    separate   out  and    carry  phosphoric  acid  with  it     separate 

when  in  the  evaporation  of  the  HC1  solution  of  the  acetate  pre- 

cipitate  the   liquid   becomes    concentrated.      To    avoid   this,   the 

evaporation  must  be  watched  very  carefully,  and  citric  acid  added 

as  soon  as  the  titanic  acid  begins  to  separate.     Then,  if  the  sepa- 

ration has  not  proceeded  too  far,  the  phosphoric  acid  may  be  pre- 

cipitated in  the  usual  way.     If,  however,  the  separation  of  titanic 

acid  is  not   checked   in   time,  proceed  with   the   evaporation   as 

directed  on  page  76,  add   5   c.c.   strong  HC1,  and  warm  gently. 

The  solution  will  nearly  always  clear,  but  if  it  does  not,  then  add 

citric  acid  and  a  slight  excess  of  ammonia,  and  filter.     Stand  the 

filtrate  aside,  burn  off  and  fuse  the  precipitate  with  Na2CO3,  dis- 

solve in  water,  filter,  acidulate  the  filtrate  with  HC1,  add  a  little 


acetate 

precipi- 


out. 


8o  THE    CHEMICAL   ANALYSIS   OF  IRON. 

Fe2Cl6  solution,  a  slight  excess  of  ammonia,  and  acidulate  with 
acetic  acid.  Boil,  filter  off  the  precipitate  of  phosphate  and  oxide 
of  iron,  dissolve  in  a  little  HC1,  allow  the  solution  to  run  into  a 
small  beaker,  evaporate  down,  and  add  it  to  the  ammoniacal 
filtrate  from  the  separated  titanic  acid  obtained  above.  Add  ex- 
cess of  magnesia-mixture,  and  precipitate  the  phosphoric  acid  in 
other  the  usual  way.  When  the  solution  becomes  cloudy  after  deoxi- 

sources    of 

error.  dation  with  NH4HSO3,  and  remains  so  after  acidulating  with  HC1, 
proceed  as  directed  above,  but  dry,  and  ignite  the  filter  containing 
the  precipitate  by  H2S  and  that  on  which  the  acetate  precipitate 
was  filtered,  fuse  with  Na2CO3,  treat  with  water,  filter,  acidulate 
with  HC1,  pass  H2S  through  the  solution,  filter,  add  a  little  Fe2Cl6 
solution,  and  precipitate  by  ammonia  and  acetic  acid.  Add  the 
solution  of  this  precipitate,  after  filtering  it  off,  to  the  solution  of 
the  main  acetate  precipitate,  and  proceed  as  before. 
Removing  Instead  of  adding  citric  acid  and  magnesia-mixture  to  the  solu- 

the  Fe  as 

Fes  before  tion  of  the  acetate  precipitate,  Fresenius,*  and  afterwards  Spiller,f 
mingle    advised  the  method  of  adding  citric  acid,  excess  of  ammonia,  and 
(NH4)2       sulphide  of  ammonium,  filtering  off  the  precipitated  sulphide  of 
P2o8.         iron,  and,  after  evaporating  to  small  bulk,  adding  magnesia-mix- 
shown  to  be   ture  and  ammonia.     When  the  bulk  of  the  iron  precipitate  is  not 
sary606        too  great,  this  is  quite  unnecessary,  for  many  determinations  have 
shown  that  with  an  excess  of  magnesia-mixture,  ammonium  mag- 
nesium phosphate  is  absolutely  insoluble  in  both   citrate  of  iron 
and  ammonium  and  citrate  of  aluminium  and  ammonium. 

The  precipitate  is  also  insoluble  in  ammonia-water  (i  part  of 
NH4HO  to  2  parts  of  water). 

The  Molybdate  Method. 

Svanberg  and  StruveJ  first  discovered  the  reaction  on  which 
this  method  is  based,  and  Sonnenschein§  first  used  it  quantita- 
tively. Weigh  5  grammes  of  drillings  into  a  No.  4  Griffin's 

*  Jour,  fur  Pr.  Chem.,  xlv.  258.  f  Jour.  Chem.  Soc.  (2),  iv.  148. 

J  Jour,  fur  Pr.  Chem.,  xliv.  291.  \  Jour,  fur  Pr.  Chem.,  liii.  339. 


ANALYSIS   OF  IRON  AND   STEEL.  gj 

beaker,  and  add,  with  the  proper  precautions  (page   58),  40  c.c. 
strong  HNO3.     Instead  of  using   HC1  to  hurry  the  solution,  it  Solution. 
is  better,  when  the  action  slackens,  to  add  water  very  cautiously 
from  time  to  time  until  the  metal  is  completely  dissolved.     Evapo- 
rate to  dryness  in  the  air-bath,  replace  the  cover,  and  heat  for  one 
hour  at  a  temperature  of  about  200°  C.  in  order  to  decompose  all 
the  carbonaceous  matter,*  otherwise  the  precipitation  of  the  phos-  Destroying 
pho-molybdate  will   be   incomplete.     Allow  the  beaker   to    cool,     bonaceous 
dissolve  the  precipitate  in  30  c.c.  HC1,  evaporate  to  dryness  to 
render  the  silica  insoluble,  redissolve  in  30  c.c.  HG1,  and  evaporate 
carefully  until  the  excess  of  HC1  is  driven  off,  shaking  the  beaker  Removal  of 
from  time  to  time  to  prevent  the  formation  of  a  crust  of  dry  chlo- 
ride of  iron.     Cool  the  beaker,  and  dilute  the  solution  with  twice 
its  volume  of  cold  water.     Filter   on   a   small,  washed   German 
filter,  3-inch  (75-mm.),  or  on  the  Gooch  crucible.     In  the  latter 
case  the  precipitation  of  the  phospho-molybdate  may  be  made  in 
the  small  flask  into  which  the  solution  is  filtered.     The  washing 
should  be  done  with  cold  water  after  dropping  a  little  dilute  HC1 
around  the  edge  of  the  filter.     The  filtrate  and  washing  should  Volume  of 

the  solu- 

not  exceed  50  or  60  c.c.  in  volume.     Add  to  the  solution  50  to     tion. 
100  c.c.  molybdate  ~solution,f  heat  it  to  40°  C.  in  a  water-bath  Temperature 

of  the  so- 

carefully  kept  at  this  temperature,  and  allow  it  to  stand  in  the     union. 
bath  for  about  four  hours.     Filter  on  a  small,  washed  filter,  and 
wash  thoroughly  with  dilute  molybdate  solution  (i   part  of  solu- 
tion to   i  part  of  water)  until  a  drop  of  the  filtrate  gives  no  re- 
action for  iron  with  ferrocyanide  of  potassium.     Stand  the  filtrate 
aside  in  a  warm  place  to  see  whether  any  further  precipitation  of 
phospho-molybdate  of  ammonium  takes  place;  if  it  does,  it  must  Solution  of 
be  filtered  off  and  treated  like  the  main  precipitate.     Pour  2  or  3     phosPho- 
c.c.  strong  NH4HO  on  the  precipitate,  stir  it  up  with  a  fine  jet  of     ™a°tey  " 

*  I  discovered  the  necessity  for  destroying  the  carbonaceous  matter  in  1877,  and 
communicated  the  fact  to  Hunt  and  Peters,  who  mentioned  it  in  the  Metallurgical 
Review,  vol.  ii.  p.  365. 

f  See  page  51. 


82  THE    CHEMICAL   ANALYSIS   OF  IRON. 

hot  water,  and  allow  the  solution  to  run  into  the  flask  or  beaker 
in  which  the  precipitation  of  phospho-molybdate  was  made. 
When  it  has  all  run  through  the  filter,  replace  the  flask  or  beaker 
by  a  small  beaker  of  a  little  over  100  c.c.  capacity,  remove  any 
phospho-molybdate  that  may  have  adhered  to  the  sides  of  the 
original  flask  or  beaker  by  means  of  the  ammoniacal  filtrate,  and 
then  pour  this  back  on  the  filter  and  allow  it  to  run  through 
into  the  small  beaker.  Wash  out  the  beaker  or  flask  with  hot 
water  and  pour  it  on  the  filter  with  the  addition  of  a  little  more 
NH4HO.  Unless  the  precipitate  of  phospho-molybdate  is  very 
large,  this  amount  of  NH4HO  should  dissolve  it,  and  a  very  little 
volume  of  more  washing  should  be  sufficient.  If  the  precipitate  is  very  large, 

the  ammo-     . 

niacaiso-  it  may  be  necessary  to  use  more  NH4HO  and  more  wash-water, 
but  under  all  circumstances  the  amount  of  NH4HO  and  of  wash- 
water  should  be  as  small  as  is  consistent  with  perfect  solution  of 
the  precipitate  and  thorough  washing  of  the  beaker  and  filter. 
When  the  precipitate  is  small,  the  filtrate  and  washings  should 
amount  to  about  25  c.c.  Neutralize  the  solution  with  strong  HC1 ; 
if  the  yellow  phospho-molybdate  begins  to  precipitate,  add  NH4HO 
until  it  redissolves,  and  if  there  should  remain  a  flocculent  white 
precipitate,  probably  silica,  after  the  solution  is  quite  alkaline,  filter 
Precipitation  it  off.  Then  to  the  cold  alkaline  liquid  add,  very  slowly,  10  c.c. 

as  Mg2(N 

H4)2p2o8.    magnesia-mixture,    stirring   constantly,    and   after    the    magnesia- 
mixture  is  all   in,  add  one-third  the  volume  of  the  solution   of 
strong    NH4HO    and    stir   vigorously.      It   is   well   to    stand   the 
beaker  in  cold  water  and  stir  the  solution  several  times  after  the 
precipitate    has  begun    to    crystallize  out.     After  standing  about 
four  hours,  it  may  be  filtered  off  on  a  very  small  ashless   filter 
and  washed  with    dilute   ammonia-water   (i    part    NH4HO   to    2 
parts  water)  containing  2.5   grammes  nitrate  of  ammonium  to  the 
Filtration       loo  c.c.     Dry,  ignite  very  carefully  to  burn  off  the  carbonaceous 
tion  of  the  matter,  and  finally  heat  for  ten  minutes   over  the  blast-lamp  to 
tete.lpl       volatilize  any  molybdic  acid  that  may  have  been  precipitated  with 
the   Mg2(NH4)2P2O8,  cool,  and  weigh.     Fill  the   crucible  half  full 


ANALYSIS   OF  IRON  AND   STEEL. 

of  hot  water,  add  5  to  20  drops  HC1,  and  heat  for  a  few  minutes 
to  dissolve  the  Mg2P2O7.  Pour  the  contents  of  the  crucible 
quickly  on  a  small  ashless  filter,  wash,  ignite,  and  weigh  the  small 
residue  that  may  remain  undissolved.  The  difference  between  the 
two  weights  is  the  weight  of  Mg2P2O7,  which  contains  27.93  per 
cent,  phosphorus. 

Many  chemists,  following  Eggertz,*  prefer  to  weigh  the  yellow  Direct 
phospho-molybdate  direct  instead  of  dissolving  it  and  precipitat- 
ing as  Mg2(NH4)2P2O8.  In  this  event  take  I  gramme  of  the  drill- 
ings and  proceed  exactly  as  directed  above,  but  use  only  about  date- 
one-third  the  amount  of  NHO3  and  HC1  for  the  solution.  Before 
adding  the  molybdate  solution,  the  volume  of  the  filtrate  from 
the  silica  should  amount  to  only  about  25  c.c.  Add  50  c.c.  of 
the  molybdate  solution,  allow  it  to  stand  four  hours  at  a  tempera- 
ture of  40°  C.,  and  filter  off  the  precipitated  phospho-molybdate 
on  a  Gooch  crucible;  wash  fin'  with  dilute  molybdate  solution, 
and  finally  with  water  containing  i  per  cent,  of  HNO3,  dry  in  an 
air-bath  heated  to  120°  C.,  and  weigh  as  (NH4)3i  iMoO3PO4  (ap- 
proximate formula),  containing  1.63  per  cent,  phosphorus.  In  the 
absence  of  a  Gooch  crucible,  use  counterpoised  filters  f  for  weigh- 
ing the  phospho-molybdate.  The  points  of  special  importance  are : 

First,  the  necessity  for  destroying  all  the  carbonaceous  matter  Precautions 

i_  r  rf  necessary. 

by  heating  the  nitric  acid  solution,  after  evaporation,  to  a  suffi- 
ciently high  temperature  to  effect  this  with  certainty. 

Second,  the  avoidance  of  an  excess  of  HC1  in  the  final  solu- 
tion before  precipitating  by  molybdate  solution. 

Third,  when  the  phospho-molybdate  is  weighed  directly,  the 
necessity  for  rendering  the  silica  insoluble. 

Fourth,  the  danger  of  heating  the  solution  above  40°  C.  after 
adding  the  molybdate  solution,  as  arsenic,  when  present,  precipi- 
tates with  the  phosphorus  if  the  solution  is  heated  to  a  higher 
temperature. 

*  Jour,  fur  Pr.  Chem.,  Ixxix.  496.  f  See  page  22. 


$4  THE    CHEMICAL   ANALYSIS   OF  IRON. 

Fifth,  the  danger  of  causing  a  precipitation  of  molybdic  acid 
with  the  phospho-molybdate  by  heating  the  solution   to   a  tem- 
perature approximating  100°  C. 
variations  Some  chemists  prefer  to  drive  off  the  HC1  entirely  by  adding 

in  the 

details.  HNO3  to  the  hydrochloric  acid  solution,  and  boiling  down  nearly 
to  dryness  once  or  twice  before  filtering  off  the  silica. 

Others,  after  filtering  off  the  silica,  add  NH4HO  until  a  slight 
permanent  precipitate  appears,  then  the  molybdate  solution,  which 
is  sufficiently  acid  to  redissolve  the  slight  precipitate  of  ferric 
hydrate,  and  leave  the  solution  quite  clear,  with  the  exception 
of  the  precipitate  of  phospho-molybdate.  Others  supersaturate 
the  hydrochloric  acid  solution  with  NH4HO,  and  redissolve  with 
the  least  possible  amount  of  NHO3  before  adding  the  molyb- 
date solution.  Many  of  these  are  matters  of  personal  preference, 
but  the  safest  plan  for  the  beginner  is  to  follow  the  instructions 
first  given  until  he  has  sufficient  knowledge  and  experience  to 
judge  of  the  value  of  these  variations,  or  to  invent  some  for 

himself. 

The  Combination  Method. 

Riley*  was  the  first  to  suggest  the  precipitation  of  phosphorus 
as  phospho-molybdate,  preceded  by  a  separation  of  the  phosphoric 
acid  from  the  mass  of  the  ferric  chloride  by  deoxidation  and  pre- 
cipitation by  the  acetate  method.  This  method  was  worked  out 
afterwards  by  A.  Wendel,  of  the  Albany  and  Rensselaer  Steel 
Company,  S.  Peters,  of  the  Burden  Iron  Company,  and  J.  L.  Smith. f 
Details  Proceed  as  directed  for  the  determination  of  phosphorus  by 

method,  the  Acetate  Method,  using  I  gramme  of  borings  and  proportional 
amounts  of  reagents  until  having  dissolved  the  acetate  precipitate 
in  HC1,  evaporate  to  dryness,  redissolve  in  a  very  little  HNO3, 
dilute  to  20  c.c.  with  water,  add  a  slight  excess  of  NH4HO,  re- 
dissolve  the  precipitated  ferric  oxide  in  HNO3,  and  add  30  c.c. 
molybdate  solution.  Heat  to  40°  C.  for  an  hour,  filter,  wash  with 
water  containing  I  per  cent,  of  HNO3,  dry,  and  weigh. 

*  Jour.  Chem.  Soc.,  1878,  vol.  i.  p.  104.  f  Chem.  News,  xlv.  195. 


ANALYSIS    OF  IRON  AND   STEEL. 

When  Titanium  is  Present. 

When  phosphorus  is  determined  in  pig-irons  containing  tita- 
nium, burn  off  the  residue  of  carbon,  silica,  etc.,  treat  it  with  HF1 
and  H2SO4,  evaporate,  and  heat  until  the  greater  part  of  the  H2SO4 
is  driven  off.  Fuse  with  2  or  3  grammes  of  carbonate  of  sodium, 
dissolve  in  water,  filter,  acidulate  the  filtrate  with  HNO3,  add  50 
c.c.  molybdate  solution,  and  heat  to  40°  C.  for  four  hours.  Filter, 
wash,  and  add  this  precipitate  to  the  one  obtained  in  the  filtrate 
from  the  carbon,  silica,  etc.  If  any  slight  insoluble  matter  should 
remain  on  the  filter  upon  dissolving  in  NH4HO  the  phospho- 
molybdate  obtained  in  the  filtrate  from  the  carbon,  silica,  etc., 
burn  it,  fuse  it  with  carbonate  of  sodium,  and  test  it  also  for  phos- 
phorus. 

As  remarked  above,  page  83,  the  formula  given  for  the  dried 
phospho-molybdate  of  ammonium  is  approximate  only.  The  Variable 
composition  of  the  salt  seems  to  vary  very  much,  the  percent- 
age  of  phosphorus  in  it  being  given  by  various  authorities  from 
1.27  to  1.75.  It  seems  to  depend  upon  various  circumstances,  date- 
such  as  the  presence  or  absence  of  HC1  in  the  solution,  the 
degree  of  acidity,  the  temperature  at  which  the  precipitation  is 
effected,  the  length  of  time  the  solution  stands  before  the  precipi- 
tate is  filtered  off,  the  size  of  the  precipitate,  the  state  of  concen- 
tration of  the  solution,  and  even  the  amounts  of  the  iron  and 
ammonium  salts  present. 

This  fact  must  be  borne  in  mind  when  the  phosphorus  is  deter-  The  precau- 
mined  by  direct  weighing  of  the  phospho-molybdate,  and  every 
effort  must  be  used  to  effect  the  precipitations  always  under  as 
nearly  as  possible  the  same  conditions. 

RAPID    METHOD.* 

This  method  gives  an  indirect  determination  of  P  by  means  of 
the  estimation  of  the  MoO3  in  the  phospho-molybdate  of  ammo- 

*  Prepared  by  Mr.  Emmerton  for  this  volume. 


86  THE   CHEMICAL   ANALYSIS   OF  IRON. 

Reduction  of  nium,  in  which  form  the  P  is  precipitated.     The  MoO3  is  reduced 

MoO3  by 

znandH2  to  a  lower  state  of  oxidation  by  the  reducing  action  of  Zn  and 
H2SO4,  and  the  reduced  oxide  is  titrated  with  a  standardized  per- 
manganate solution,  MoO3  being  again  formed  by  the  reaction. 

The  ratio  of  P  to  MoO3  in  the  yellow  precipitate  being  known, 
the  amount  of  P  present  may  easily  be  calculated  when  the 
amount  of  MoO3  is  known. 

The  MoO3  is  not  reduced  by  Zn  and  H2SO4  to  Mo2O3,  but  to  a 
mixture  of  oxides  corresponding  to  the  formula  Mo12O19. 

The  action  of  permanganate  on  this  oxide  is  as  follows : 

5Mo12O19  +  !7(K2OMn2O7)  =  6oMoO3-f  i;K2O  +  34MnO. 
17  molecules  of  permanganate  being  equivalent  to  60  molecules 
of   MoO3>    I    molecule  of  permanganate,  which   can   oxidize   560 
parts  of  iron,  oxidizes  Mo12Ol9  to  508.23  parts  MoO3.     Hence  a 
solution  of  permanganate  has  a  strength,  in  terms  of  MoO3,  90.76 
per  cent,  of  its  strength  against  iron.     The  phospho-molybdate 
contains  24MoO3  to  iP2O5,  the  phosphorus  being  1.794  per  cent, 
of  the  MoO3. 
Oxidation  of          por   convenience   in    reckoning,   a   permanganate   solution    is 

Mo12019  to 

Mo63by     used  of  which   I  c.c.  =  .0001  P.     Its  strength  against  iron  is  I  c.c. 

ganate.  =.oo6i4i  Fe.  Its  strength  against  MoO3  is  90.76  per  cent,  of 
this,  or  .005574  MoO3.  1-794  per  cent,  of  this,  — .0001,  is  its 
strength  against  P. 

In  the  case  of  steel,  dissolve  5  grammes,  in  a  6-inch  dish,  in 
75  c.c.  HNO3  of  i. 20  specific  gravity.  Support  a  6-inch  watch- 
glass  over  the  dish,  so  that  the  edge  of  the  glass  is  about  half  an 
inch  above  the  rim  of  the  dish.  Boil  down  rapidly  on  an  iron 
plate,  and  heat  thirty  minutes  on  the  hot  plate  after  the  residue 
looks  dry.  At  the  end  of  this  time  the  smell  of  acid  should  have 
Details  disappeared.  Let  the  dish  cool,  add  40  c.c.  strong  HC1,  put  the 

of  the 

method.  cover  down  tight  on  the  dish,  and  heat  at  a  gentle  temperature  for 
a  few  minutes,  till  the  oxide  of  iron  spattered  on  the  cover  is 
softened,  then  boil  down  till  all  but  15  c.c.  of  the  acid  is  gone. 
The  latter  part  of  the  process  requires  close  attention,  as  it  is 


ANALYSIS   OF  IRON  AND   STEEL.  87 

necessary  that  at  its  completion  the  solution  should  be  very  con- 
centrated, and  yet  that  there  should  be  very  little  chloride  dried 
upon  the  sides  of  the  dish.  Let  the  dish  cool  a  little,  lift  up  the 
large  watch-glass,  and  rinse  off  the  lower  side  of  it  with  40  c.c. 
strong  HNO3,  wrhich  is  allowed  to  flow  into  the  dish.  Then 
cover  the  solution  with  an  inverted  watch-glass  I  inch  smaller  in 
diameter  than  the  dish,  so  that  in  the  subsequent  boiling  down  of 
the  solution  the  liquid  condensing  on  the  inner  side  of  the  watch- 
glass  will  run  back  to  the  sides  of  the  dish  instead  of  to  the 
middle,  and  will  thus  aid  in  preventing  the  formation  of  a  crust 
about  the  edge  of  the  liquid.  Place  the  dish  thus  covered  on  a  solution 
hot  plate,  and  boil  the  solution  down  to  about  15  c.c.  in  bulk.  Lmpk. 
Take  the  dish  from  the  plate,  and  move  it  about  so  as  to  moisten 
with  the  solution  what  crust  may  have  formed.  In  this  way,  with 
a  little  skill,  a  perfectly  clear  and  highly  concentrated  solution 
may  be  obtained, /from  which,  practically,  all  the  HC1  has  been 
expelled. 

Dilute  this  solution,  when  somewhat  cooled,  to  about  40  c.c. 
with  water,  and  wash  it  into  a  400  c.c.  flask,  bringing  the  solution 
to  about  75  c.c.  Add  strong  ammonia,  shaking  after  each  addi- 
tion to  make  a  thorough  mixture  of  the  ammonia  with  the  pre- 
cipitated ferric  hydrate.  Continue  adding  ammonia,  shaking  after 
each  addition,  till  the  mass  sets  to  a  stiff  jelly,  then  add  a  few  c.c. 
more,  shake  well,  and  be  satisfied  that  there  is  a  strong  smell  of 
ammonia  in  excess.  Then  add  strong  HNO3  gradually,  shaking 
well  after  each  addition,  until  the  liquid  begins  to  get  thinner. 
After  the  precipitate  has  all  dissolved  and  the  solution  shows  a 
very  dark  color,  add  a  little  more  HNO3,  enough  to  bring  the  so- 
lution to  a  clear  amber  color.  At  this  stage  the  solution  will  be 
150  to  300  c.c.,  generally  about  250  c.c.,  in  bulk.  Put  a  thermome-  Precipitation 
ter  into  the  liquid  and  observe  its  temperature:  if  below  85°  C., 
heat  carefully  over  a  lamp-flame  till  it  is  raised  to  this  temperature; 
if  above  85°  C.,  cool  to  that  temperature  by  immersion  of  the  flask 
in  water.  When  at  85°,  add  at  once  40  c.c.  of  molybdate  solu- 


38  THE   CHEMICAL  ANALYSIS   OF  IRON. 

tion.*  Close  the  flask  with  a  rubber  stopper,  wrap  it  in  a  thick 
cloth,  and  shake  up  and  down  violently  for  five  minutes.  At  the 
end  of  this  time  the  precipitate  will  be  all  down. 

Collect  the  precipitate  on  a  filter,  using  the  filter-pump,  and 
wash  thoroughly  with  HNCJf  diluted  with  fifty  times  its  bulk  of 
water.  No  difficulty  is  experienced  in  getting  practically  all  of  the 
precipitate  from  the  flask  to  the  filter.  If  a  thin  film  of  the  pre- 
cipitate should  adhere  to  the  walls  of  the  flask,  it  may  be  removed 
by  a  portion  of  the  ammonia  used  in  dissolving  the  yellow  pre- 
cipitate previous  to  the  reduction  with  zinc  and  sulphuric  acid. 
Have  ready  a  500  c.c.  flask  in  which  have  been  put  10  grammes  of 

Reduction  of  granulated  zinc,  roughly  weighed  out.  Put  the  moist  filter  with  the 
precipitate  on  a  funnel  in  the  neck  of  this  flask ;  punch  a  hole  in 
the  point  of  the  filter,  and  wash  the  precipitate  into  the  flask  with 
ammonia,  I  in  4.  This  can  be  done  thoroughly  without  using 
more  than  30  c.c.  ammonia.  Then  pour  into  the  flask  80  c.c.  hot 
dilute  sulphuric  acid,  I  in  4,  and  cover  the  neck  with  a  small  fun- 
nel. Heat  quickly  on  an  iron  plate  till  rapid  solution  of  the  zinc 
begins,  and  then  heat  gently  for  ten  minutes.  At  the  end  of  this 
time  the  reduction  is  complete.  To  separate  the  liquid  from  the 
undissolved  zinc,  pour  it  through  a  large  folded  filter,  rinse  the 
flask  with  cold  water,  and,  after  these  washings  have  run  through, 
fill  up  the  filter  once  with  cold  water.  The  filtration  on  a  large 
folded  filter  exposes  the  liquid  but  a  very  short  time  to  the  air. 
The  zinc  is  decanted  into  the  filter  with  the  liquid,  on  which  it 
continues  to  act  till  the  latter  has  drained  through. 

Titration  by         The  filtrate,  amounting  to  400-500  c.c.,  is  then  ready  for  titra- 
ganate  so-  tion  with  permanganate,  which  is  run  in  until  the  liquid  is  color- 
less.     During  the  reduction   of  the   MoO3  the   liquid   takes   on 
successively  the  colors   pink,  plum,   pale   olive-green,   and    dark 
olive-green,  the   darkness   of  the   final    color  depending   on    the 

*  The  molybdate  solution  used  is  made  by  dissolving  100  grammes  molybdic  acid 
in  a  mixture  of  300  c.c.  strong  ammonia  and  100  c.c.  water,  and  pouring  this  solution 
into  1250  c.c.  HNO3  of  1.20  specific  gravity. 


ANALYSIS  OF  IRON  AND   STEEL.  go 

amount  of  MoO3  reduced.  The  moment  the  reduced  liquid  is 
exposed  to  the  air  on  the  filter  it  loses  its  green,  and  takes  on  a 
port-wine  color,  but  this  change  does  not  seem  to  be  due  to  an 
appreciable  amount  of  oxidation,  the  oxidation  of  the  reduced 
liquid  taking  place  slowly,  as  was  shown  by  Werncke. 

In  titrating,  the  wine  color  becomes  fainter,  and  finally  dis- 
appears, leaving  a  perfectly  clear  liquid,  in  which  one  drop  of 
permanganate  produces  a  plain  pink  color. 

In  the  case  of  irons,  dissolve  5  grammes,  and  get  the  HNO3  Pig-iron, 
solution  as  described  above.  Wash  this  into  a  graduated  100 
c.c.  flask,  dilute  to  the  mark,  mix,  pour  through  a  dry  filter  into 
a  dry  bottle,  using  the  filter-pump.  From  the  filtrate  draw  off 
80  c.c.  with  a  pipette,  and  in  this  amount,  holding  4  grammes  of 
the  iron  taken  for  analysis,  finish  the  determination.  In  this  way 
what  may  be  a  tedious  filtration  and  washing  is  avoided,  and  the 
bulk  of  the  solution  is  kept  constant.  . 

In  the  case  of  ores,  dissolve  10  grammes  in  HC1,  evaporate  iron-ores. 
to  dryness,  take  up  with  HC1,  evaporate  to  small  bulk,  and  expel 
the  HC1  by  boiling  down  with  40  c.c.  strong  HNO3.     Then  filter 
from  the  insoluble  residue  before  going  on  with  the  determination. 

A  mechanical  device  may  be  used  for  shaking  the  flasks  during  Machine  for 
precipitation,  which  is  very  convenient,  especially  when  a  great 
many  determinations  have  to  be  made.  It  consists  of  a  box,  the 
inside  of  which  is  about  three-fourths  of  an  inch  higher  and  one- 
half  of  an  inch  wider  than  the  stoppered  flask.  It  has  a  door  in 
front,  which  closes  tight ;  a  leather  strap,  having  a  loop  in  the 
middle  just  large  enough  for  the  neck  of  the  flask  to  pass 
through,  is  placed  in  the  box  so  that  one  end  is  fastened  perma- 
nently to  the  box  on  one  side,  and  the  other  end  passes  out  on 
the  other  side,  and  is  fastened  on  the  outside  of  the  box  by  a 
screw-clamp.  In  putting  the  flask  into  the  box  the  neck  is  passed 
up  through  the  strap,  and  the  free  end  of  the  strap  on  the  outside 
is  pulled  down  tight,  till  the  flask  is  pressed  firmly  on  the  bottom 
of  the  box.  The  strap  is  then  held  securely  in  place  by  the  com- 

7 


THE   CHEMICAL   ANALYSIS   OF  IRON. 

pression  of  the  screw-clamp.  The  box,  which  may  have  two  or 
more  such  compartments  in  it,  is  mounted  on  an  upright  which 
slides  between  guides  and  is  given  an  up-and-down  stroke  of 
about  six  inches  by  a  simple  arrangement  of  pulleys  and  a  crank. 
When  run  at  about  100  strokes  per  minute,  it  gives  a  very  satis- 
factory shaking.  It  takes  only  a  few  seconds  to  fasten  a  flask  into 
the  box,  and  as  many  more  to  take  it  out.  This  appliance  thus 
saves  considerable  time  and  exertion. 

The  box  prevents  any  considerable  loss  of  heat  during  the 
shaking,  so  that  the  liquid  is  kept,  during  the  precipitation,  be- 
tween the  limits  of  temperature  which  insure  a  precipitate  of 
correct  composition. 


DETERMINATION    OF    MANGANESE. 

The  Acetate  Method. 

Dissolve   I   gramme  of  drillings  in    15  c.c.  HNO3,   1.2  sp.  gr., 
in  a  No.  2  Griffin's  beaker.     Evaporate  to  dryness  in  the  air-bath, 
and  heat  to   decompose  carbonaceous  matter.     Allow  the  beaker 
to  cool,  add  10  c.c.  HC1,  heat  carefully  until  all  the  Fe2O3  is  dis- 
solved, evaporate  to  dryness  to  get  rid  of  all  the  HNO3,  redissolve 
in  10  c.c.  HC1,  and  evaporate  carefully  until  the  solution  is  almost 
syrupy.     Dilute  with  cold  water  to  about   100  c.c.,  and  filter  off 
the  insoluble  matter,  allowing  the  filtrate  and  washing  to  run  into 
For  steel  and  a  No.  6   Griffin's  beaker.     In  the  case  of  steel  or  puddled  iron 
fron  fihra-    the  filtration  may  be  omitted,  the  solution  being  poured  into  the 
ne^sTry    large  beaker,  and  the  rinsings  of  the  small  beaker  added.     To  the 
solution  in  the  large  beaker,  which  should  amount  to  about  200 
c.c.,  add  a  solution  of  carbonate  of  sodium  very  slowly,  stirring 
Nemraiiza-     vigorously.     The  solution  will   finally  become  very  dark   red  in 
Na2co3.      color,    and   the    precipitate   formed   will    redissolve   very   slowly. 
Add  the  solution  of  carbonate  of  sodium  2  or  3  drops  at  a  time, 
stir  well,  and  allow  the  solution  to  stand  several  minutes,  to  see 


ANALYSIS   OF  IRON  AND   STEEL.  oj 

whether  the  precipitate  will  redissolve  or  not.     When,  under  these 

circumstances,  a  decided  precipitate  remains,  add  2  drops  of  HC1, 

stir  well,  and  allow  the  solution  to  stand  for  some  minutes ;  if  the 

solution  does  not  clear,  add  2  drops  more,  and  stir  again.     If  the 

first   part   of    the   operation    has   been    carefully   conducted,  this 

amount  of  HC1  will  usually  be  sufficient,  but  if,  for  any  reason, 

too   large  a  precipitate  has  been   formed,   it  may  require  a  few 

drops   more.     It   is    important,   however,   that  no    more   HC1  be  importance 

added  than  just  enough  to  redissolve  the  precipitate  formed  by     fog  excess 

the  carbonate  of  sodium,  and,  to  insure  this,  the  solution  should 

be  well  stirred  and  allowed  to  stand  a  sufficient  length  of  time. 

after  each  addition   of   HC1.     The  solution  may  be  so  dark  in 

color  that  it  is  difficult  to  see  when  the  precipitate  does  finally 

disappear,  but  by  standing  the  beaker  on  a  piece  of  white  paper 

the  light  reflected  through  the  bottom  of  the  beaker  will  greatly 

diminish  the  difficulty.     When,  under  this  method  of  procedure, 

the  solution  clears,  add  2  grammes  of  acetate  of  sodium  dissolved 

in  a  few  c.c.  of  water,  stir  well,  and  dilute  the  solution  to  about 

700  c.c.  with  boiling  water.     Heat  it  to  boiling,  and  allow  it  to 

boil    for   about    ten    minutes,  then    remove   it    from   the   tripod, 

and   allow  the   precipitated    hydrate   and   basic   acetate   of   iron 

to  settle.     Decant  the  clear,  supernatant  fluid  on  a  large  washed  Filtering  off 

German  filter,  throw  the  precipitate  on,  and  wash  it  two  or  three     solving  the 

times  with  boiling  water,  allowing  the  filtrate  to  run  into  a  large 

beaker  or  flask,  from  which  it  can  be  transferred  to  a  platinum 

or  porcelain  dish  and  evaporated  rapidly.     When  the  precipitate 

has  drained  quite  dry,  by  means  of  a  platinum  spatula  transfer 

it   to   the    beaker   in   which    the    precipitation    was    first   made ; 

dissolve  the  precipitate  which  remains  adhering  to  the  filter,  and 

that  which  remains  on  the  blade  of  the  spatula,  by  pouring  around 

the  edge  of  the  filter  and  on  the  spatula  held  over  it  10  c.c.  HC1 

diluted  with  twice  its  volume  of  hot  water,  allowing  it  to  run  into 

the  beaker  containing  the  precipitate.     Wash  the  filter  free  from 

chloride  of  iron  with  cold  water,  and  heat  the  beaker  containing 


^2  THE   CHEMICAL   ANALYSIS   OF  IRON. 

the  precipitate  until  the  latter  is  dissolved.  Cool  the  solution, 
and  repeat  the  precipitation,  filtration,  and  resolution  of  the  pre- 
cipitate precisely  as  in  the  first  case,  adding  this  filtrate  to  the 

Evaporation   first  one.     Precipitate,  filter,  and  wash  a  third  time  in  the  same 
trates.        manner,  evaporate  all  the  filtrates   down  together  until  they  are 
reduced  to  about  300  c.c.  in  volume,  and  transfer  this  solution  to 
a  No.  3  beaker. 

If  any  manganese  has  become  oxidized  during  the  evapora- 
tion by  exposure  to  the  air,  it  forms  a  hard  ring  on  the  side  of 
the  capsule,  and  may  be  dissolved,  after  the  solution  is  poured 
into  the  beaker,  by  two  or  three  drops  of  HC1,  and  washed  into 
the  beaker.  Should  any  oxide  of  iron  separate  out,  run  the  solu- 
tion in  the  capsule  through  a  small  filter,  allowing  it  to  run  into 
the  beaker,  wash  the  precipitate  with  hot  water,  dissolve  it  in  a 
very  few  drops  of  dilute  HC1,  and  let  it  run  into  a  No.  I  beaker. 
Add  just  enough  solution  of  carbonate  of  sodium  to  precipitate 
it,  make  it  faintly  acid  with  acetic  acid,  boil  it,  and  filter  into  the 
main  solution. 

This  solution  now  contains  all  the  manganese,  nickel,  and 
cobalt  and  the  greater  part  of  the  copper  which  may  have  been 

Separation  of  in  the  metal.     Add  to  it  10  grammes  of  acetate  of  sodium  and  a 

and  Co'       few  drops  of  acetic  acid,  heat  it  to  boiling,  and  pass  a  current  of 

M™111        H2S   through  the  boiling  solution  for  fifteen  minutes.     This  will 

precipitate  the  copper,   cobalt,  and   nickel.     Filter  off  the  black 

sulphides,  boil   the   filtrate   to    expel  the  excess  of  H2S,  let  the 

solution    cool    somewhat,  and  add   bromine-water   in    excess.     If 

Precipitation  no  precipitate  forms  at  first,  stand  the  solution,  which  should  be 

of  MnOo 

by  Br.  colored  by  the  bromine-water,  in  a  warm  place  for  an  hour  or  two, 
to  allow  the  precipitate  of  MnO2  to  separate  out.  If  a  precipitate 
forms  immediately,  add  bromine-water  until,  when  the  precipitate 
settles,  the  solution  is  strongly  colored  by  it,  and  stand  it  aside 
for  an  hour  or  two.  At  the  end  of  this  time,  the  precipitate 
having  settled  and  the  supernatant  fluid  being  still  colored  by 
the  bromine,  heat  it  carefully,  finally,  to  boiling  and  expel  the 


ANALYSIS   OF  IRON  AND   STEEL.  03 

excess  of  bromine ;  allow  the  precipitate  to  settle,  filter,  wash  very 
carefully,  and  avoid  stirring  up  the  precipitate  when  it  is  on  the 
filter,  as  it  has  a  tendency  to  go  through.  Dissolve  the  precipitate 

v  \    ' 

on  the  filter  in  sulphurous  acid  water  containing  a  little  HC1 ; 
allow  the  solution  to  run  into  a  platinum  dish,  and  wash  the  filter 
well.  A  little  of  the  SO2  water  will  quickly  dissolve  any  MnO2 
which  may  adhere  to  the  beaker  in  which  it  was  precipitated,  and 
this  may  be  poured  on  the  filter.  Boil  the  solution  in  the  dish  to 
expel  the  excess  of  SO2,  add  5  to  20  c.c.  of  a  clear  filtered  solu- 
tion of  microcosmic  salt,  heat  to  boiling,  and  add,  with  constant 
stirring,  NH4HO  drop  by  drop.  When  the  precipitate  of  phos-  Precipitation 
phate  of  ammonium  and  manganese  begins  to  form,  stop  adding  H4)2pjo8 
NH4HO,  and  stir  until  the  precipitate  becomes  crystalline.  When 
this  change  occurs,  add  one  more  drop  of  NH4HO ;  the  additional 
precipitate  formed  will  be  curdy,  but  a  few  seconds'  continued 
stirring  at  the  boiling  temperature  will  change  it  to  the  silky 
crystalline  condition.  Continue  the  addition  of  NH4HO  in  ex- 
actly this  manner  until  the  precipitate  is  all  down  and  further 
additions  of  NH4HO  fail  to  change  the  silky  appearance.  Add 
a  dozen  drops  of  NH4HO  in  excess,  remove  the  dish  from  the 
light,  and  stand  it  in  ice-water  until  perfectly  cold.  Filter  on  an  Solution  ot 
ashless  filter,  wash  with  cold  water  containing  10  grammes  of  for  wash- 
nitrate  of  ammonium  (dissolved  in  water  made  faintly  alkaline  with 
NH4HO  and  filtered)  in  100  c.c.  until  the  filtrate  gives  no  re- 
action for  HC1,  dry,  ignite,  and  weigh  as  Mn2P2OT,  which  contains 
38.73  per  cent.  Mn.  During  the  precipitation  of  the  phosphate 
of  ammonium  and  manganese  the  stirring  must  not  be  discon- 
tinued for  an  instant,  as  the  solution  has  a  great  tendency  to  bump 
when  the  precipitate  is  allowed  to  settle.  The  crystalline  condi- 
tion of  the  precipitate,  which  is  absolutely  necessary  for  the  suc- 
cess of  the  determination,  can  be  most  readily  brought  about  by 
the  means  described  above.  It  can,  of  course,  be  accomplished 
by  adding  an  excess  of  NH4HO  at  once,  but  it  will  require  much 
more  boiling  and  stirring  than  the  method  above  described.  The 


94  THE    CHEMICAL   ANALYSIS   OF  IRON. 

final  precipitation  as  phosphate  of  ammonium  and  manganese, 
due  to  Dr.  Gibbs,  is  much  the  most  accurate  method  known.  A 
Weighing  as  common  practice,  however,  is  to  wash  the  bromine  precipitate  of 
hydrated  binoxide  of  manganese,  dry,  ignite,  and  weigh  as  Mn3O4, 
objections  which  contains  72.05  per  cent.  Mn.  There  are  two  objections  to 
this  method  of  procedure :  first,  the  difficulty  of  washing  the 
MnO2  free  from  sodium  salts ;  secondly,  the  uncertainty  as  to  the 
exact  state  of  oxidation  of  the  ignited  oxide  of  manganese.  The 
first  of  these  objections  Eggertz  claims  to  overcome  by  washing 
the  precipitated  MnO2  with  water  containing  I  per  cent,  of  HC1. 
It  may  also  be  overcome,  or  rather  the  danger  may  be  avoided,  by 
using  no  fixed  alkalies.  By  this  method,  nearly  neutralize  the 
HC1  solution  of  the  iron  or  steel  by  NH4HO,  then  add  a  solution 
of  carbonate  of  ammonium  exactly  as  directed  above  for  car- 
Avoiding  use  bonate  of  sodium,  and  finally,  instead  of  acetate  of  sodium,  add 
alkalies.  acetate  of  ammonium  (5  c.c.  of  NH4HO  slightly  acidulated  by 
acetic  acid).  Evaporate  the  filtrates  obtained  in  this  way  to  about 
500  c.c.,  transfer  to  a  flask  of  about  I  litre  capacity,  and  cool. 
When  perfectly  cold,  add  3  or  4  c.c.  bromine,  shake  well,  and  when 
the  solution  is  strongly  colored  all  through  by  bromine,  add  an 
excess  of  NH4HO,  and  heat  to  boiling.  Filter,  wash  with  hot 
water,  dry,  ignite,  and  weigh  as  Mn3O4. 

variable  The  second  objection  seems,  according  to   Pickering,*  to  be 

tion  of  ig-    well    founded,  the  amount  of   manganese   in  the  ignited   oxides 

ide  of  X      varying  from  69.688  per  cent,  to  74.997  per  cent.,  according  to  the 

temperature  to  which  they  were  heated  and  other  undetermined 

Weighing  as  conditions.     This  cause  of  error  may  be  avoided  by  weighing  the 

precipitate  as  MnS,  containing  63.22  per  cent.  Mn.     This  method, 

due  to  H.  Rose,f  is  carried  out  as  follows :  Ignite  the  oxide  in  a 

porcelain  crucible,  allow  it  to  cool,  mix  it  with  5  or  6  times  its 

volume  of  flowers  of  sulphur,  place  the  crucible  on  a  triangle,  and 

insert   the   bowl   of  a  clay  tobacco-pipe,   which   should  be  large 

*  Chem.  News,  xliii.  226.  f  Rose,  Quant.  Anal.  (French  ed.),  p.  104. 


ANAL  YSIS   OF  IRON  AND   STEEL.  ^ 

enough  to  quite  fill  the  top  of  the  crucible  and  too  large  to  reach 
to  the  precipitate.  Pass  through  the  stem  a  current  of  dry  hydro- 
gen until  all  air  is  expelled,  heat  the  crucible  gradually  to  as  high 
a  heat  as  a  good  Bunsen  burner  will  produce,  cool  in  the  current 
of  hydrogen,  and  weigh  as  MnS. 

General  Remarks  on  the  Acetate  Method. 

The  chief  source  of   error  in   the   acetate   method,  as   it   is  Source  of 
usually   practised,   is   in   the    addition   of   too    much   acetate   of     acetate 
sodium,  whereby  the  manganous  chloride  is  changed  to  manga- 
nous   acetate,   which,   according  to    Kessler,*  is    readily  decom- 
posed to  manganous  oxide  and   acetic   acid.      Under  these  cir- 
cumstances, a  larger  amount  of  manganese  is  precipitated  with 
the  iron  than  would  be  the  case  if  a  less  amount  of  acetate  of 
sodium  were  added.     When  acetate  of  sodium  is  added  to  ferric 
chloride,  the  reaction  may  be  written,  6NaC2H3O2,3H2O  +  Fe2Cl6  Amount  of 

NaC2 

=  6NaCl-}- Fe2(C2H3O2)6+ 3H2O;  and  to  precipitate  the  iron  as  H8o2 
ferric  acetate  in  I  gramme  of  metal  would  necessitate  the  use  of 
8  grammes  of  acetate  of  sodium.  But,  as  Kessler  in  the  same 
article  remarks,  when  a  solution  of  ferric  chloride  is  treated  with 
carbonate  of  sodium  and  HC1  exactly  as  described  above,  a  liquid 
is  formed  which  contains  14  times  its  equivalent  of  ferric  hydrate  in 
solution.  Consequently  ^  gramme  of  acetate  of  sodium  would 
be  sufficient  to  precipitate  I  gramme  of  iron  as  ferric  hydrate 
and  basic  acetate.  In  order,  however,  to  precipitate  the  manga- 
nese as  MnO2  by  bromine,  it  is  necessary  to  convert  all  the  man- 
ganous chloride  into  manganous  acetate :  consequently  an  excess 
of  acetate  of  sodium  is  added  before  adding  bromine.  If,  when 
making  the  acetate  precipitation,  the  solution  contains  any  ferrous 
chloride,  a  brick-dust  precipitate  is  usually  formed,  which  gener-  Brick-dust 

prccipi- 

ally  passes  through  the  filter,  and  is  very  difficult  to  dissolve  or     tate. 
manage  in  any  way.     It  is  usually  the  shortest  and  best  plan,  in 
this  event,  to  start  a  fresh  portion  and  throw  away  the  other. 

*  Chem.  News,  xxvii.   14. 


96 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


Method  for 
steel  and 
puddled 


Filtering  the 
cold  solu- 
tion. 


Effect  of 
N2O3  in 
HN03. 


The  Nitric  Acid  and  Chlorate  of  Potassium  Method. 

(Ford*s  Method?) 

The  acetate  method  is  at  best  very  tedious,  and  when  the 
amount  of  manganese  is  very  small  it  is  of  course  desirable  to 
work  on  larger  amounts  than  I  gramme  of  the  sample,  but  the 
iron  precipitate  in  this  event  is  so  large  that  it  becomes  very  diffi- 
cult to  manage  it  properly.  With  Ford's  method,  however,  there 
is  almost  no  limit  to  the  amount  which  can  be  operated  upon, 
and  many  experiments  have  shown  that  with  proper  precautions 
it  is  an  extremely  accurate  process.  The  reaction  on  which  the 
process  is  based  was  first  noticed  by  Hannay  *  in  1878 ;  but  Fordf 
first  worked  out  the  method  in  its  present  practical  form.  Dis- 
solve 5  grammes  of  borings  in  a  No  3  beaker  in  60  c.c.  HNO3,  1.2 
sp.  gr.,  evaporate  down  until  the  solution  is  almost  syrupy,  then 
add  100  c.c.  strong  HNO3,  1.4  sp.  gr.,  and  5  grammes  KC1O3. 
Stand  the  beaker  on  a  tripod  with  a  thin  piece  of  sheet  asbestos, 
about  i  inch  (25  mm.)  in  diameter,  in  the  centre  of  the  wire  gauge 
or  on  the  air-bath,  and  heat  the  solution  to  boiling.  Boil  the  solu- 
tion fifteen  minutes,  remove  the  light,  add  50  c.c.  strong  HNO3 
and  5  grammes  KC1O3,  replace  the  light,  and  boil  fifteen  minutes 
longer,  or  until  the  yellowish  fumes  from  the  decomposition  of  the 
KC1O3  are  no  longer  given  off.  Cool  the  solution  as  rapidly  as 
possible  by  standing  the  beaker  in  cold  water,  filter  on  the  pump, 
using  the  conej  or  glass  filtering-tube  with  asbestos  filter,§  and 
wash  two  or  three  times  with  strong  HNO3,  which  must  be  free 
from  nitrous  fumes.||  Nitrous  acid  reduces  MnO2  to  MnO,  which 
then  dissolves  in  HNO3.  Its  presence  may  be  recognized  by 
the  yellow  color  it  imparts  to  HNO3,  and  it  may  be  removed 
by  blowing  air  through  the  acid.  It  is  always  formed  in  HNO3 

*  Jour.  Chem.  Soc.,  xxxiii.  269.  f  Trans.  Inst.  Min.  Engineers,  ix.  397. 

|  See  page  21.  \  As  described  under  Methods  for  Determination  of  Carbon. 

||  It  is  always  well  to  transfer  the  filtrate  and  washings  to  a  No.  4  beaker,  add  2 
grammes  KC1O3,  and  boil  again,  to  see  whether  any  further  precipitate  of  MnO2  is  formed. 


ANALYSIS   OF  IRON  AND   STEEL.  gy 

which  has  been  exposed  to  sunlight,  and  for  that  reason  this 
acid  should  be  kept  in  a  dark  place.  Suck  the  precipitate  dry, 
and  transfer  it,  with  the  asbestos  filter,  to  the  beaker  in  which  the 
precipitation  was  made.  Pour  into  the  beaker  10  to  40  c.c.  strong 
sulphurous  acid  water,  which  will  dissolve  the  precipitate  almost 
instantly.  By  pouring  it  through  the  cone  or  filtering-tube,  any 
adhering  precipitate  will  be  dissolved  and  carried  into  the  beaker. 
As  soon  as  the  precipitate  is  dissolved,  add  2  to  5  c.c.  HC1,  and 
filter  from  the  asbestos  into  a  No.  I  beaker,  washing  with  hot 
water.  Heat  the  filtrate  until  the  excess  of  SO2  is  driven  off,  add 
bromine-water  until  the  solution  is  strongly  colored  with  it,  and 
boil  off  the  excess  of  bromine.  Add  NH4HO  until  the  solution  Separation 

..  .  -.,.__  from  small 

smells  quite  strongly  of  it,  boil  for  a  few  minutes,  and  filter  into      amounts  of 

a  No.  3  beaker.     Wash  several  times  with  hot  water,  remove  the     NH°HO^ 

beaker,  dissolve  the  ferric  hydrate  on  the  filter  in  dilute  hot  HC1 

(i  part  of  acid  to  3  of  water),  allowing  the  solution  to  run  back 

into  the  beaker  in  which  the  precipitation  was  made,  and  wash  the 

filter  with  hot  water.     Boil  this  filtrate  for  a  few  minutes  to  drive 

off  the  chlorine  which  may  be  present  from  the  solution  of  any 

little  MnO2  precipitated  with  the  ferric  hydrate,  reprecipitate  by 

NH4HO  as  before,  filter,  and  repeat  the  solution,  precipitation,  and 

filtration,  allowing  all  the  filtrates  from  the  ferric  hydrate  to  run 

into  the   No.   3    beaker.     Acidulate  this  solution,  which  will  be 

about  300  or  400  c.c.  in  volume,  with  acetic  acid,  heat  to  boiling, 

and   pass   H2S   through   the   boiling   solution  for   ten    or   fifteen 

minutes.     Filter  into  a  platinum  dish  from  any  sulphide  of  cobalt,  separation 

from  co- 

which  is  the  only  metal  likely  to  be  present  with  the  manganese ;     bait. 
boil  off  the  H2S  after  adding  a  little  HC1,  add  microcosmic  salt, 
and  precipitate,  filter,  ignite,  and  weigh,  as  directed  on  page  93, 
as  Mn2P2O7. 

Steels  containing  much  Silicon. 

In  steel  high  in  silicon,  0.2  per  cent,  and  over,  the  gelatinous 
silica  formed  is  very  apt  to  clog  the  filter  when  operating  as  de- 
scribed above,  and  it  is  better  to  dissolve  the  sample  in  HC1, 


THE   CHEMICAL   ANALYSIS   OF  IRON. 

evaporate  to  dryness,  being  careful  not  to  heat  it  too  hot,  redis- 
solve  carefully  in  50  c.c.  strong  HNO3,  boil  down  until  nearly 
syrupy  to  destroy  all  the  HC1,  redissolve  in  100  c.c.  strong  HNO3, 
and  precipitate  as  directed  above. 

Pig-iron. 

Dissolve  5  grammes  in  50  c.c.  dilute  HC1  (i  part  HC1  to  I 
part  water);  filter  on  a  washed  German  filter  into  a  No.  3  beaker, 
evaporate  to  dryness,  redissolve  in  50  c.c.  strong  HNO3,  and  pro- 
ceed as  in  the  case  of  "  steel  hih  in  silicon." 


met 


Spiegel  and  Ferro-mangancse. 

It  is  best  to  use  only  I  gramme  of  spiegel  or  ferro-manganese 
of  20  to  40  per  cent,  manganese  and  .5  gramme  of  very  high,  60 
Variation  in   to  80  per  cent,  ferro-manganese.     In  the  latter,  indeed,  it  is  better 
ethod  for  to  use  the  acetate  method  with  NH4HO  and   NH4C2H3O2,  and, 
omitting  the  precipitation  by  bromine,  boil  off  the  H2S  from  the 
filtrate  from  the  insoluble  sulphides,  after  adding  HC1,  and  then 
precipitate  by  microcosmic  salt  as  directed  above. 

RAPID    METHODS. 
Volumetric  Methods. 

Volhard's  Method* 

This  method  is  based  on  the  principle  announced  by  Morawski 
and  Stingl,f  that  when  permanganate  of  potassium  is  added  to  a 
neutral  manganous  salt  all  the  manganese  is  precipitated,  in  accord- 
ance with  the  reaction  4KMnO4+6MnSO4  +  4H2O:=  ioMnO2  + 


4KHSO4-|-  2H2SO4.  When  all  the  manganous  salt  is  oxidized, 
the  solution  is  colored  by  the  permanganate,  which  thus  indi- 
cates the  end  reaction.  The  permanganate  used  for  titrating  iron 
ores  may  be  used  for  this  determination,  and,  its  value  being 

*  Liebig's  Annalen,  Band  cxcviii.  p.  318;  Chem.  News,  xl.  207. 
•f-  Chem.  News,  xxxviii.  297. 


ANALYSIS   OF  IRON  AND   STEEL.  gg 

determined,  as  directed,  in  terms  of  Fe,  the  calculation  for  Mn 

is  as  follows :    The  reaction,  when  permanganate  is  added  to  a  Calculation 

of  strength 

solution  of  ferrous  sulphate,  is  ioFeSO4+  2KMnO4-f  8H2SO4=  ofperman- 
5Fe2(SO4)3+2MnSO4+K2SO4+8H2O,  or  2  molecules  of  perman- 
ganate oxfdize  10  molecules  of  FeSO4.  Now,  as  2  molecules  of 
permanganate  oxidize  3  molecules  of  manganous  sulphate,  while 
2  molecules  of  permanganate  oxidize  10  molecules  of  ferrous  sul- 
phate, the  oxidizing  power  of  the  permanganate  is  only  three- 
tenths  as  great  in  the  former  case  as  it  is  in  the  latter,  and  its 
value  in  Mn  is  to  its  value  in  Fe  as  3  is  to  10,  or  |-f  ^  A 
Therefore  the  value  of  the  permanganate  in  Fe  multiplied  by 
or  0.2946=  its  value  in  Mn.  Dissolve  1.5  grammes  of  borings  in  Details 
a  platinum  or  porcelain  dish  in  25  c.c.  HNO3,  1.2  sp.  gr.  When  method. 
solution  is  complete,  add  12  c.c.  dilute  H2SO4  (i  part  concentrated 
H2SO4  and  I  part  water),  and  evaporate  to  dryness,  as  directed  on 
page  15,  heating  until  fumes  of  H2SO4  are  given  off  in  order  to 
destroy  all  the  carbonaceous  matter.  Or  dissolve  in  HNO3  as 
above,  evaporate  to  dryness,  and  heat  on  the  tripod  until  the  car- 
bonaceous matter  is  destroyed;  dissolve  in  15  c.c.  HC1,  add  12  c.c. 
dilute  H2SO4  as  above,  and  evaporate  until  fumes  of  H2SO4  are 
given  off.  Allow  tHe  dish  to  cool,  add  100  c.c.  water,  and  heat 
until  all  the  ferric  sulphate  is  dissolved?!!  Wash  into  a  carefully 
graduated  300  c.c.  flask,  so  that  with  the*washings  the  solution 
may  not  exceed  200  c.c.  in  volume,  and  add  solution  of  carbonate 
of  sodium  until  the  precipitate  which  is  first  formed  dissolves  only 
with  difficulty.  Then  add  slowly  zinc  oxide*  suspended  in  water, 
shaking  well  after  each  addition  until  the  iron  is  precipitated, 
which  will  be  shown  by  the  sudden  coagulation  of  the  solution. 
The  precipitate  will  then  settle,  leaving  a  slightly  milky  super- 
natant liquid.  Fill  the  flask  exactly  to  the  mark  on  the  neck 
(300  c.c.),  and  mix  thoroughly  by  pouring  the  entire  contents  of 
the  flask  into  a  large,  clean,  dry  beaker,  and  back  again  into  the 

*  See  page  5 1. 


IOQ  THE    CHEMICAL   ANALYSIS   OF  IRON. 

flask,  repeating  this  several  times.  Allow  the  precipitate  to  settle 
for  a  few  minutes,  and  pour  the  solution  through  a  large,  dry  filter. 
Fill  a  200  c.c.  pipette  with  this  filtrate,  which  will,  of  course,  rep- 
resent exactly  I  gramme  of  the  sample,  run  it  into  a  flask  of 
about  500  c.c.  capacity,  heat  to  boiling,  and  add  2  drops  of  HNO3, 
sp.  gr.  1.2.  Now  add  permanganate  solution  slowly  from  a 
burette,  shaking  after  each  addition  to  mix  the  solution  and  facili- 
tate the  collection  of  the  precipitated  hydrated  peroxide  of  man- 
ganese. When  the  reaction  is  nearly  finished,  the  solution  will  be 
slightly  colored  by  the  permanganate,  but  the  color  disappears 
after  shaking  the  flask  and  allowing  it  to  stand  for  a  moment. 
Finally,  however,  a  drop  or  two  will  give  the  solution  a  permanent 
pink  color,  which  will  not  disappear  for  several  minutes.  The 
number  of  c.c.  of  the  permanganate  solution  used  multiplied  by 
the  factor  found  (the  Fe  factor  of  the  permanganate  multiplied  by 
.2946)  is  the  amount  of  manganese  in  the  sample.  If,  during  the 
addition  of  the  permanganate,  the  solution  should  become  cool 
and  the  precipitate  fail  to  collect  and  settle  quickly,  heat  the  solu- 
Appiicabie  tion,  but  not  quite  to  the  boiling-point.  This  method  is  appli- 
forvery  cable  for  all  samples  except  those  containing  very  minute  amounts 
amounts  °f  nianganese.  In  working  on  spiegel,  take  .75  gramme,  then, 
>f  Mn-  using  two-thirds  of  the  filtrate,  the  amount  will  be  calculated  on 
.5  gramme. 

Williams 's  Method. 

This  method,  which  consists  in  precipitating  the  MnO2  by 
Ford's  method,  filtering,  washing,  dissolving  in  H2SO4  with  a 
measured  volume  of  some  reducing  agent,  such  as  oxalic  acid  or 
ferrous  sulphate,  and  titrating  the  excess  by  permanganate,  was 
first  used  by  Williams.*  Regarding  the  precipitate  by  KC1O3  in  a 
nitric  acid  solution  as  MnO2,  the  reaction  in  dissolving  it  might  be 
expressed  thus:  MnO2-f-2FeSO4-f-2H2SO4=MnSO4+  Fe2(SO4)3 
+  2H2O,  or  MnO2  +  H2C2O4  +  H2SO4=  MnSO4  +  2CO2  +  2H2O. 

*  Trans.  Inst.  Min.  Engineers,  x.  100. 


ANALYSIS   OF  IRON  AND   STEEL.  IOI 

Therefore    I   molecule  of  MnO2  oxidizes   2   molecules  of  ferrous  Oxidizing 
sulphate,  or   I   molecule  of  oxalic  acid  and  the  excess  of  oxalic      MnO2. 
acid  or  ferrous  sulphate  unoxidized  having  been  determined  by  a 
solution  of  permanganate,  the  difference  between  this  excess  and 
the  amount  originally  added  is  the  amount  oxidized  by  the  MnO2. 

We  therefore  require  two  standard  solutions,  one  of  perman-  standard  so- 
ganate  and  one  of  ferrous  sulphate,  ammonium  ferrous  sulphate,  quired. 
or  oxalic  acid.  The  permanganate  solution  used  for  iron  deter- 
minations answers  perfectly.  A  solution  of  ferrous  sulphate  is 
perhaps  the  most  satisfactory,  and  is  prepared  by  dissolving  10 
grammes  of  the  crystallized  salt,  Fe$O4,7H2O,*  in  900  c.c.  water 
and  100  c.c.  strong  H2SO4.  It  will  keep  perfectly  in  a  glass-stop- 
pered bottle  in  the  dark  for  a  long  time.  One  c.c.  of  this  solution 
will  be  equal  to  about  .002  gramme  Fe,  or  nearly  .001  gramme 
Mn,  and  if  the  permanganate  is  of  the  usual  strength,  say  I  c.c.= 
.007  gramme  Fe,  I  c.c.  of  the  permanganate  will  equal  about  3.5 
c.c.  of  the  ferrous  sulphate.  The  permanganate  solution  having  standard- 
been  carefully  standardized,  measure  50  c.c.  of  the  ferrous  sulphate 
solution  by  means  of  a  pipette  into  the  dish,f  dilute  to  about  I 
litre,  and  run  in  permanganate  solution  from  a  burette,  stirring 
constantly  until  the  first  permanent  pink  tint  appears.  The  read- 
ing of  the  burette  will  give  the  value  of  50  c.c.  ferrous  sulphate  in 
permanganate,  and  consequently  by  a  simple  calculation  its  value 
in  Fe  and  Mn.  Suppose,  for  instance,  I  c.c.  permanganate  solu- 
tion =.0068  gramme  Fe,  or  (according  to  the  proportion  given 
above,  112  :  55  ::  Fe  :  Mn)  — .00334  gramme  Mn.  Then  if  14.1  c.c. 
permanganate  =50  c.c.  ferrous  sulphate,  100  c.c.  ferrous  sulphate 
will  be  equivalent  to  28.2  c.c.  permanganate.  In  using  oxalic 
acid,  dissolve  2.25  grammes  of  the  crystallized  acid,  H2C2O4,2H2O, 
in  i  litre  of  wrater,  and  determine  its  strength  by  measuring  50  c.c. 
into  the  dish,  diluting  with  hot  water,  adding  5  c.c.  H2SO4,  and 
titrating  with  permanganate. 

*  See  page  48.  f  See  Determination  of  Iron  in  Iron  Ores. 


102 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Details  The   details    of   the    method   are   as    follows :    Weigh    out    5 

of  the 

method.  grammes  of  the  sample  of  puddled  iron,  pig-iron,  or  steel,  and 
proceed  as  directed  on  p.  96  ct  seq. ;  but  after  filtering  and  washing 
the  precipitated  MnO2  with  strong  HNO3,  suck  the  precipitate  as 
dry  as  possible,  and  then  wash  out  the  beaker  in  which  the  precipi- 
tation was  made  with  cold  water.  Pour  this  water  on  the  precipi- 
tate, and  repeat  the  operation  two  or  three  times  to  get  rid  of  all 
the  HNO3.  Suck  the  precipitate  as  dry  as  possible,  transfer  it  with 
the  asbestos  to  the  beaker  in  which  the  precipitation  was  made, 
measure  into  the  beaker  100  c.c.  of  the  standard  ferrous  sulphate 
solution  (or  100  c.c.  oxalic  acid  solution  and  10  c.c.  H2SO4),  and 
stir  until  the  MnO2  is  all  dissolved.  When  using  oxalic  acid  it 
is  necessary  to  heat  gently  to  about  60°  C.  Wash  the  solution 
and  asbestos  into  the  dish,  dilute  to  about  I  litre  (with  oxalic 
Example.  acid  use  hot  water),  and  titrate  with  permanganate.  We  will  sup- 
pose, for  example,  that  it  requires  10.2  c.c.  permanganate  to  give 
the  permanent  rose  tint;  then,  as  100  c.c.  ferrous  sulphate  =  28.2 
c.c.  permanganate,  there  would  be  the  equivalent  of  28.2 — 10.2 
=  18  c.c.  of  permanganate  in  ferrous  sulphate  oxidized  by  the 
MnO2  precipitate.  One  c.c.  of  permanganate  being  equivalent  to 
.00334  gramme  Mn,  18  c.c.  =  . 060 12  gramme  Mn,  and,  5  grammes 
of  the  sample  having  been  taken,  .060 12  -7-5  =  .01202  X  100=  1.202 
per  cent.  Mn. 

Spiegel  and  Ferro-manganese. 

When  working  on  spiegel  or  ferro-manganese,  take  .5  gramme 

of  the  sample  and  proceed  in  the  same  manner  as  directed  for 

steel  or  iron ;  but  it  is  better  to  use  a  standard  solution  of  ferrous 

sulphate  containing  30  grammes  of  FeSO4,7H2O  to  the  litre  for 

composition    very  high  ferro-manganese. 

Meof°X~  ^S  t^iere  seems  to  be  some  uncertainty  as  to  the  exact  com- 

position of  the  oxide  of  manganese,*  the  permanganate  solution 

*  Stone,  Trans.  Inst.  Min.  Engineers,  xi.  323,  xii.  295,  514;    Mackintosh,  Trans. 
Inst.  Min.  Engineers,  xii.  79,  xiii.  39. 


ANALYSIS   OF  IRON  AND   STEEL. 

may  be  standardized  as  follows :   Determine  the  absolute  amount  standard- 
of  manganese  in  a  finely-ground  and  well-mixed  sample  of  Spiegel     spiegei  of 
or  ferro-manganese  by  a  gravimetric  method,  then  treat  .5  gramme     Jj°™ 
of  the  same  sample  exactly  as  described  above,  and,  having  found 
the  number  of  c.c.  of  permanganate  that  are  equivalent  to  100  c.c. 
of  the  ferrous  sulphate  solution,  the  amount  of  manganese  in  the 
sample  divided  by  the  number  of  c.c.  of  permanganate  equivalent 
to  the  ferrous  sulphate  oxidized  by  the  oxide  of  manganese  in  the 
sample,  gives  the  value  of  the  permanganate  solution.  t  Thus,  if 
100  c.c.  ferrous  sulphate  solution  require  28.2  c.c.  permanganate 
to  give  the  rose  tint  upon  titration,  the  sample  of  spiegei  contains 
14.50  per  cent.  Mn,  and  the  ferrous  sulphate  remaining  after  the 
solution  of  the  oxide  of  manganese  in   100  c.c.  requires   6.5  c.c. 
permanganate  to  give  the  rose  tint  upon  titration  (using  .5  gramme 
of  the  sample,  of  which  I  gramme  contains  .1450  gramme  Mn),  the 
calculation  would  be  as  follows:    28.2  c.c.  —  6.5  c.c.  =  2 1.7  c.c.  =  Example. 
.0725  gramme  Mn,  or  I  c.c.  permanganate  is  equivalent  to'^v^  = 
.00334  gramme  Mn. 

Pattisoris  Method  (for  Spiegel  and  Ferro-manganese). 
This  method  is  based  on  the  precipitation  of  manganese  as 
MnO2,  from  a  solution  of  MnCl2,  by  hypochlorite  of  calcium  and 
carbonate  of  calcium  in  the  presence  of  ferric  chloride  (the  pres- 
ence of  the  latter  salt  or  of  chloride  of  zinc  being  necessary  to 
prevent  the  precipitation  of  any  manganese  in  a  lower  state  of 
oxidation  than  MnO2).*     Dissolve  .5  gramme  of  spiegei  or  ferro-  Details 
manganese  in  a  No.  5  beaker  in  15  c.c.  HNO3,  1.2  sp.  gr.,  evapo-     method. 
rate  to  dryness,  and  heat  to   destroy  carbonaceous  matter.     Re- 
dissolve  in  HC1,  and  boil  down  to  remove  HNO3,  but  not  to  dry- 
ness,  add  a  few  drops  of  HC1,  and  dilute  with  10  c.c.  water.     Add 
carbonate  of  calcium  diffused  in  water  until  the  solution  becomes 
reddish  by  neutralization  of  the  free  acid,  then  add  5  or  6  drops 
HC1  and  100  c.c.  of  a  solution  of  bleaching  powder  (hypochlorite 

*  Jour.  Chem.  Soc.,  xxxv.  365. 


THE    CHEMICAL   ANALYSIS   OF  IRON. 

of  calcium),  made  by  treating  15  grammes  of  the  powder  with  i 
litre  of  water  and  filtering.  Now  pour  in  about  300  c.c.  of  boiling 
water,  which  will  raise  the  temperature  of  the  solution  to  about 
70°  C,  and  add  carbonate  of  calcium,  with  constant  stirring,  until 
all  the  iron  is  precipitated.  If  the  supernatant  fluid  has  a  pink 
color,  due  to  the  formation  of  a  little  permanganate,  add  a  few 
drops  of  alcohol,  which  will  reduce  it.  Filter  on  a  large  filter, 
wash  until  the  filtrate  is  free  from  chlorides,  place  the  filter  and 
its  contents  in  the  beaker  in  which  the  precipitation  was  made, 
and  add  100  c.c.  of  standard  solution  of  ferrous  sulphate,  made 
as  directed  on  page  101.  When  the  precipitate  is  dissolved, 
transfer  the  solution  to  the  dish,  dilute  to  about  I  litre,  titrate 
the  excess  of  ferrous  sulphate  as  directed  on  page  101,  and  calcu- 
late the  percentage  of  Mn  as  there  directed. 

The  Color  Method  (for  Steel). 

This  method  was  first  suggested  by  Pichard,*  and  was  used 
essentially  in  its  present  form  by  Peters. f  It  is  now  in  very  gen- 
eral use  in  steel-works,  and  takes  rank  with  the  color  carbon 
method  in  its  usefulness.  It  requires  one  or  more  standard  steels 
in  which  the  manganese  has  been  most  carefully  determined  by 
a  gravimetric  method.  When  a  number  of  samples  are  to  be 
tested  at  the  same  time,  as  is  usually  the  case,  a  bath  like  the  one 
shown  in  Fig.  71  is  necessary,  but  for  the  manganese  color 
Chloride  of  method  it  should  contain  a  solution  of  chloride  of  calcium,  which 
bath  boils  at  115°  C.J  It  is,  of  course,  very  necessary  in  a  method 
of  this  kind  that  the  operations  should  always  be  conducted  as 
nearly  as  possible  under  the  same  conditions,  and  that  the 
standard  should  always  be  dissolved  at  the  same  time  as  the 
samples  to  be  tested.  Weigh  out  .2  gramme  of  each  sample  and 

*  Comptes-Rendus  Hebd.  des  Stances  de  1'Acad.  des  Sciences,  Dec.  30,  1872. 
•f  Chem.  News,  xxxiii.  35. 
This  latter  modification  is  due  to  Mr.  S.  A.  Ford. 


ANALYSIS   OF  IRON  AND   STEEL.  IQ^ 

of  the  standard,  and  place  them  in  8-inch  test-tubes  properly  Details 
numbered.  Pour  into  each  test-tube  15  c.c.  HNO3,  1.2  sp.  gr.,  method, 
cover  each  with  a  small  glass  bulb  or  very  small  funnel,  and 
stand  the  test-tubes  in  the  holes  in  the  top  of  the  bath,  as  shown 
in  the  sketch,  Fig.  71.  Heat  in  the  bath  at  100°  C.  until  solution 
is  complete.  Pour  the  contents  of  a  test-tube  into  a  100  c.c.  tube, 
wash  the  test-tube  out  with  cold  water,  adding  it  to  the  solution 
in  the  100  c.c.  tube,  and  finally  dilute  to  the  100  c.c.  mark.  Mix 
thoroughly  by  placing  the  thumb  over  the  top  of  the  tube  and 
turning  it  upside  down  several  times.  Draw  out  10  c.c.  of  this 
solution  with  a  pipette  graduated  to  deliver  10  c.c.,  and  let  it  run 
into  the  test-tube  in  which  the  solution  was  made.  Treat  each 
sample  in  this  way,  including  the  standard.  The  tube  is  merely 
washed  out  with  water,  but  the  pipette  can  be  best  cleaned  by 
drawing  it  full  from  the  100  c.c.  tube  of  the  fresh  sample,  throw- 
ing the  contents  away,  and  filling  it  a  second  time  to  deliver  into 
the  test-tube.  Stand  the  test-tubes  in  the  rack  again,  add  to  each 
3  c.c.  HNO3,  1.2  sp.  gr.,  replace  the  bulbs  or  funnels,  and  stand 
the  rack  in  the  chloride  of  calcium  bath,  the  solution  in  which 
should  now  be  boiling.  When  the  solutions  in  the  test-tubes  begin 
to  boil,  add  to  each  .5  gramme  fine  peroxide  of  lead*  and  boil 
exactly  five  minutes.  The  PbO2  can  readily  be  measured  by  a 
small  platinum  spoon,  made  to  hold  about  .5  gramme.  It  is  Necessity  for 

boiling  the 

necessary  that  the  solutions  in  the  test-tubes  should  boil,  and  it  solutions 
is  easy  to  assure  one's  self  of  this  fact  by  looking  down  into  the 
test-tubes  after  the  action  caused  by  the  addition  of  the  PbO2  has 
ceased.  Remove  the  rack  from  the  bath  at  the  expiration  of  the 
five  minutes,  and  stand  it  with  the  test-tubes  in  cold  water,  to  cool 
the  solutions  and  allow  the  insoluble  lead  salt  to  settle.  The  in- 
soluble matter  settles  to  the  bottom  of  the  tube  in  a  heavy  com- 
pact mass,  leaving  the  supernatant  fluid  perfectly  clean.  When 
this  occurs,  which  is  usually  within  the  space  of  half  an  hour,  the 


*  See  page  50. 
8 


I06  THE    CHEMICAL   ANALYSIS   OF  IRON. 

solutions  are  ready  to  be  decanted  into  the  comparison-tubes.*  In 
working  on  a  number  of  steels  we  will  suppose  that  we  use  two 
standards,  one  containing  1.2  per  cent,  of  manganese,  the  other 
.6  per  cent.  As  we  weighed  out  .2  gramme,  diluted  the  solution 
to  100  c.c.,  and  took  10  c.c.  in  which  to  determine  manganese,  the 
amount  taken  corresponds  to  0.02  gramme  of  the  sample ;  and  if 
we  dilute  the  solutions  of  the  standards  after  decanting  into  the 
comparison-tubes  to  24  c.c.,  one  c.c.  will  correspond  to  .05  per 
cent,  in  the  high,  and  .025  per  cent,  in  the  low,  standard.  Decant 
each  solution  in  turn  into  a  comparison-tube,  and  dilute  it  until  it 
Comparing  has  the  exact  tint  and  depth  of  color  of  the  standard  to  which  it 

the  colors.  . 

most  nearly  approximates  when  first  decanted.  The  percentage  of 
manganese  is  found  by  multiplying  the  number  of  c.c.  to  which  the 
sample  has  been  diluted  by  .05  or  .025,  according  to  the  standard 
with  which  it  has  been  compared.  If,  however,  the  solution  of  a 
sample  when  first  decanted  and  before  dilution  should  be  lighter 
in  color  than  the  lower  standard,  the  latter  may,  after  the  other 
samples  have  all  been  finished,  be  diluted  to  30  c.c.,  when  each 
c.c.  will  correspond  to  .02  per  cent,  manganese,  or,  if  this  color 
is  not  sufficiently  light,  to  40  c.c.,  when  each  c.c.  will  correspond  to 
.015  per  cent,  manganese.  When  even  this  color  is  not  sufficiently 
light,  a  lower  standard  must  be  used  for  comparison,  or  a  larger 
amount  of  the  sample  taken  for  solution.  The  comparison  of  the 
colors  should  be  made  in  a  camera  or  box,  as  shown  in  Fig.  73. 
The  direct  rays  of  the  sun  should  not  be  allowed  to  shine  on 
the  solutions,  and  a  northern  light  for  the  comparisons  is  prefer- 
able to  any  other. 


DETERMINATION    OF    CARBON. 

The  con-  Carbon  differs  from  all  other  elements  in  iron  and  steel  in  that 

ft  is  supposed  to  exist  in  several  conditions,  and  analytical  chemis- 
-  try  SUppiies  the  means  of  distinguishing  between  at  least  two  of 

*  See  Fig.  72. 


ANALYSIS   OF  IRON  AND   STEEL. 
these  conditions.     Until  within  a  few  years  it  was  considered  to      ists  in  iron 

and  steel. 

exist  in  two  forms,  as  graphite  and  as  combined  carbon.  To 
Karsten  is  due  the  recognition  of  the  fact  that  graphite  is  a  form 
of  pure  carbon,  and  not  a  compound  of  carbon  and  hydrogen. 
It  is  always  present  as  a  mechanical  mixture,  and  is  thus  distin- 
guished from  the  other  form,  which  was  supposed  to  be  combined 
chemically  with  the  iron.  Of  late  years  the  opinion  has  been 
growing  that  "  combined  carbon"  exists  in  at  least  two  conditions 
in  steel,  but  as  yet  chemical  methods  for  separating  and  distin- 
guishing between  these  conditions  have  failed,  so  far  as  quanti- 
tative work  is  concerned.  The  analytical  methods  here  given 
are: 

The  Determination  of  Total  Carbon, 

The  Determination  of  Graphitic  Carbon,  and 

The  Determination  of  Combined  Carbon. 

DETERMINATION  OF  TOTAL  CARBON. 

We  may  divide  the  methods  for  the  determination  of  total 
carbon  in  iron  and  steel  into  the  following  classes: 

A.  The  direct  treatment  of  the  borings  or  drillings  without 
previous  separation  of  the  iron,  including: 

1.  Direct  combustion  in  a  current  of  oxygen  (Berzelius). 

2.  Combustion  with  chromate  of  lead  and  chlorate  of  potas- 
sium (Regnault). 

3.  Combustion  with  oxide  of  copper  in  a  current  of  oxygen 
(Kudernatsch). 

4.  Solution  and  oxidation  of  the  borings  by  CrO3  and  H2SO4 
(Brunner  modified  by  O.  Gmelin). 

B.  Removal  of  the  iron  by  volatilization,  and  subsequent  com- 
bustion of  the  carbon,  including : 

1.  Volatilization  in  a  current  of  chlorine  (Berzelius,  Wohler). 

2.  Volatilization  in  a  current  of  hydrochloric  acid  gas  (Deville). 

C.  Solution  of  the  iron,  and  combustion  or  weighing  of  the 
residue,  including: 


IO3  THE    CHEMICAL   ANALYSIS  OF  IRON. 

1.  Solution  in  double  chloride  of  copper  and  ammonium,  filtra- 
tion,   and  weighing   or   combustion   of   the   residue  (Pearce   and 
McCreath). 

2.  Solution  in  chloride  of  copper  and  chloride  of  sodium  or 
potassium,   filtration,   and   combustion   of  the    residue   in   oxygen 
(Richter). 

3.  Solution  in  chloride  of  copper,  and  combustion  of  the  resi- 
due (Berzelius). 

4.  Solution  in  iodine  or  bromine,  and  combustion  with  chro- 
mate  of  lead,  or  weighing,  of  the  residue  (Eggertz). 

5.  Solution  by  fused  chloride  of  silver,  and  combustion  of  the 
residue  (Berzelius). 

6.  Solution  of  the  iron  in  sulphate  of  copper,  filtration,  and 
combustion   of   the    residue   in    a   boat   in    a  current  of   oxygen 
(Langley). 

7.  Solution  of  the   iron   in   sulphate  of  copper,  and  oxidation 
of  the  residue  by  CrO3  and   H2SO4  (Ullgren). 

8.  Solution  of  the  iron  in  sulphate  of  copper,  filtration,  and  com- 
bustion of  the  residue,  mixed  with  oxide  of  copper  in  vacuo  under 
the  Sprengel  pump,  the  volume  of  CO2  being  measured  (Parry). 

9.  Solution!  in  dilute  HC1  by  the  aid  of  an  electric  current,  and 
combustion  of  the  residue  (Binks,  Weyl). 

10.  Oxidation  of  the  iron  by  atmospheric  air  and   moisture, 
solution  of  the  ferric  oxide  by  HC1,  filtration,  and  combustion  of 
the  residue  (Berthier). 

A.    1.    Direct  Combustion  in  a  Current  of  Oxygen. 
Necessity  This  method  requires  the  sample  to  be  reduced  to  a  very  fine 

for  pow- 
dering the    state  of  subdivision,  otherwise  some  of  the  metal  in  the  centre  of 

the  lumps  becomes  coated  with  oxide,  and  the  carbon  in  it  escapes 
combustion.  Weigh  out  into  a  porcelain  or  platinum  boat,  about 
3  inches  (75  mm.)  long,  I  to  3  grammes  of  the  sample,  and  spread 
it  as  evenly  as  possible  over  the  bottom  of  the  boat.  Place  the 
boat  in  the  porcelain  tube  B,  Fig.  54,  by  means  of  the  rod  C, 


ANALYSIS   OF  IRON  AND   STEEL.  IOg 

replace  the  stopper  P,  and  turn  on  a  current  of  oxygen  from  the  Details 
cylinder  O,  the  stopcock  R  being  open  and  Q  closed.  The  ap-  method, 
paratus  will  now  appear  as  in  the  cut.  The  description  of  the 
apparatus  is  given  on  page  115^  seq.,  the  only  difference  being 
that  for  this  determination  the  U-tube  H  and  roll  of  silver  in  the 
tube  B  are  omitted.  The  precautions  necessary  in  weighing  the 
absorption  apparatus,  consisting  of  the  bulb  I  and  tube  J,  are  also 
described  fully  on  page  119.  When  the  tube  is  full  of  oxygen, 
the  absorption  apparatus  being  weighed  and  attached,  light  the 
burners  in  the  furnace,  beginning  at  the  forward  end,  and,  when 
they  are  all  lighted,  maintain  the  temperature  of  the  tube  at  a 
good  red  heat  for  thirty  minutes.  Should  the  solution  in  the  bulb 
I  begin  to  recede,  owing  to  the  rapid  absorption  of  oxygen  by 
the  metal  in  the  boat,  increase  the  flow  of  oxygen,  and  regulate 
it  so  that  the  gas  may  never  pass  through  the  bulb  I  more  rapidly 
than  3  or  4  bubbles  in  a  second.  At  the  expiration  of  the  thirty 
minutes,  shut  off  the  current  of  oxygen  at  O,  close  the  stopcock 
R,  open  Q,  and  start  the  current  of  air  by  opening  T  gradually, 
so  that  the  water  may  flow  into  the  lower  bottle  F.  Turn  down 
the  lights  in  the  furnace  slowly,  to  avoid  cracking  the  tube,  finally 
turn  them  out,  and  allow  the  current  of  air  to  run  through  the 
apparatus  until  the  oxygen  is  expelled.  This  will  usually  be 
accomplished  by  running  out  half  the  water  in  the  bottle  F. 
Close  the  stopcock  T,  remove  the  absorption  apparatus,  and  weigh 
it.  The  increase  of  weight  will  be  CO2,  due  to  the  carbon  in  the 
sample,  and  it  contains  27.27  per  cent,  carbon. 

2.    Combustion  with  Chr ornate  of  Lead  and  Chlorate  of 

Potassium. 

This  method,  like  the  preceding  one,  requires  the  sample  to  be  Preparation 
very  finely  powdered.     Take  a  piece  of  combustion-tubing  about     comtms- 
32  inches    (800  mm.)  long,  y2   inch  (12  mm.)  internal  diameter,   • 
and  y^g-  inch  (1.5   mm.)  thick  in  the  walls;  heat  it  in  the  middle 
by  means  of  a  blast-lamp  until   it  softens,   draw  the  ends  apart 


I  10 


THE    CHEMICAL   ANALYSIS  OF  IRON. 


Details 
of  the 
method. 


FIG.  49. 


slightly,    and   then,   keeping   the   ends  parallel,   draw    it    out,    as 
shown  in  Fig.  49.     Allow  it  to  cool,  scratch  it  in  the  middle  with 

a  file,  and  break  it. 
This  gives  two  tubes 
each  about  16  inches 
(400  mm.)  long.  Fuse 
the  large  ends  slightly 
so  as  to  round  the  sharp  edges,  but  avoid  contracting  the  tube. 
Wash  the  tubes  thoroughly,  using  a  rod  with  a  piece  of  dark- 
colored  silk  or  linen  on  the  end ;  then  if  any  lint  remains  on  the 
inside  of  the  tube  it  can  be  easily  seen.  Dry  the  tubes  by  heating 
them  carefully  and  drawing  air  through  them,  then  fuse  the  small 
ends  and  cork  the  large  ends  to  keep  out  the  dust.  Weigh  out  I 
to  3  grammes  (i  gramme  of  pig-iron,  spiegel,  or  ferro-manganese, 
3  grammes  of  steel)  of  the  sample,  and  grind  it  thoroughly  in 
a  small  mortar  with  15  times  its  weight  of  fused  and  powdered 
chromate  of  lead  and  I  y2  times  its  weight  of  fused  and  powdered 
chlorate  of  potassium  or  bichromate  of  potassium.  Bichromate 
of  potassium  is  to  be  preferred,  as  a  little  chlorine  is  sometimes 
given  off  by  chlorate  of  potassium  when  used  in  this  manner. 
Place  the  combustion-tube  in  a  stand,  as  shown  in  Fig.  50,  and 
FIG.  50.  push  down  into  the  end,  with  a  clean 

glass  rod,  a  little  ignited  asbestos. 
The  asbestos  should  not  be  tightly 
packed,  as  it  will  prevent  the  air  from 
passing  in  freely  at  the  end  of  the 
operation.  Place  a  small,  dry,  per- 
fectly clean  funnel  in  the  end  of  the 
tube,  and  pour  through  it  enough  of 
the  pure  powdered  chromate  of  lead 
to  fill  the  tube  for  about  one  inch  of 
its  length.  Hold  the  mortar  under 
the  funnel  so  that  anything  that  falls 
from  it  may  go  into  the  mortar,  and  charge  the  mixture  into 


ANAL  YSIS  OF  IRON  AND   STEEL.  !  1 1 

the  tube  by  means  of  a  small  platinum  spatula.  Clean  out  the 
mortar  by  grinding  in  it  two  or  three  successive  small  portions  of 
chromate  of  lead,  charging  each  into  the  tube  through  the  funnel. 
Remove  the  funnel,  cork  the  tube,  and,  holding  it  in  a  hori- 
zontal position  with  the  tail  up,  tap  it  gently  to  get  a  clear  space 
for  the  passage  of  the  gas  from  one  end  of  the  tube  to  the  other. 
Place  the  tube  in  the  combustion-furnace,  remove  the  cork,  and 
insert  in  its  place  a  smooth  velvet  cork,  through  the  centre  of 
which  passes  one  end  of  a  Marchand  U-tube.  The  half  of  this 
tube  nearest  the  combustion-tube  contains  pumice  saturated  with 
anhydrous  sulphate  of  copper,*  and  the  other  half  granulated 
dried  chloride  of  calcium,  the  two  reagents  being  separated  by 
a  small  plug  of  fibrous  asbestos  loosely  packed.  Weigh,  and 
attach  the  absorption  apparatus  and  safety-tube.  Apply  suction  at 
the  end  of  the  rubber  tube  on  the  forward  end  of  the  safety-tube, 
and  draw  a  few  bubbles  of  air  through  the  potash-bulb.  Allow 
the  liquid  to  recede  gradually;  if  it  maintains  its  level  in  the 
bulb  for  a  few  minutes,  the  joints  of  the  apparatus  may  be  con- 
sidered tight,  but  if  it  gradually  falls,  it  is  proof  that  there  is  a 
leak,  and  the  joints  must  all  be  tightened.  If,  after  pushing  the  Testing  the 
cork  as  far  as  possible  into  the  end  of  the  combustion-tube  and  Of  the  con- 
binding  all  the  rubber  connections,  another  trial  still  shows  a  leak, 
a  fresh  cork  must  be  substituted.  When  the  joints  are  all  tight, 
light  the  burner  at  the  forward  end  of  the  tube,  and  each  burner 
successively  as  the  flow  of  gas  slackens,  bringing  the  tube  over 
each  burner  to  a  red  heat  before  lighting  the  next  one.  Maintain 
the  whole  length  of  the  tube  up  to  the  asbestos  at  a  good  red  heat 
until  the  flow  of  gas  entirely  ceases.  Then  pass  a  piece  of  rubber 
tubing  attached  to  a  purifying  apparatus  well  over  the  tail  of  the 
tube,  which  should  be  cool  enough  to  be  handled,  break  the  point 
of  the  tail  inside  the  tubing,  lower  the  lights  a  little,  and,  by  means 
of  the  aspirator-bottles,  force  about  I  litre  of  air  through  the 

*  See  page  46. 


112 


THE    CHEMICAL  ANALYSIS   OF  IRON. 


Details 
of  the 
method. 


Using  a 
current  of 
oxygen. 


apparatus.     It  will  now  appear  as  in  Fig.  51.     Turn  out  the  lights, 
and  detach  and  weigh  the  absorption  apparatus,  with  the  precau- 

FIG.  51. 


tions  mentioned  on  page  119.  The  increase  of  weight  will  be  the 
CO2  due  to  the  carbon  in  the  sample.  This  contains  27.27  per 
cent,  carbon. 

3.    Combustion  with  Oxide  of  Copper  in  a  Current  of 

Oxygen. 

Prepare  the  combustion-tube  as  directed  in  the  last  method, 
and  pour  on  the  asbestos  in  the  end  of  the  tube  enough  oxide  of 
copper  to  fill  the  tube  to  the  height  of  about  an  inch  (25  mm.). 
Mix  the  weighed  sample,  I  to  3  grammes  in  a  fine  state  of 
division,  with  at  least  20  times  its  weight  of  finely-powdered 
pure  oxide  of  copper,  charge  it  into  the  tube  as  directed  on  page 
no,  rinse  out  the  mortar  with  a  little  more  of  the  same  material, 
and  finally  fill  the  tube  to  within  an  inch  (25  mm.)  of  the  end  with 
granulated  oxide  of  copper.  Make  the  combustion  exactly  as 
directed  in  the  last  method,  page  in.  If  the  combustion  is  to  be 
made  in  a  current  of  oxygen,  which  is  much  the  best  plan,  instead 
of  drawing  the  combustion-tube  out  to  a  point  and  sealing  it,  it 
may  be  drawn  out  straight,  as  shown  in  Fig.  52.  In  this  case, 
FIG.  52.  attach  to  the  drawn-out  end  when 

t)  ^==-    the  tube  is  in  the  furnace  a  purify- 

ing apparatus  for  oxygen  and  air,  as  shown  in  Fig.  54,  and  con- 
duct the  operation  as  directed  on  page  109. 


ANALYSIS   OF  IRON  AND   STEEL. 


4.    Solution  and  Oxidation  of  the  Borings  by  CrO3 
and  H2SO4. 

Fig.  5  3  shows  the  details  of  the  apparatus  for  carrying  out  this  Description 
method.     M  is  the  U-tube  for  purifying  the  air.     It  contains  fused     apparatus. 
caustic  potassa.     A  is  the  flask  for  oxidizing  and  dissolving  the 
sample.      The  piece  of  glass  tubing  N  bent  at  a  right  angle  is 
drawn  out  slightly  at  the  lower  end,  over  which  a  piece  of  soft 
gum  tubing  is  fitted,  forming  a  stopper,  which  fits  tightly  in  the 
top  of  the  bulb-tube  when  air  is  forced  through  the  apparatus. 
B  is  a  bulb-tube  for  introducing  the  reagents.     The  lower  end  is 
drawn  out  so  that  the  orifice  is  quite  small.     O  contains  strong 
H2SO4,  P  contains  dry  pumice,  Q  granular  chloride  of  calcium, 
and   the   small   bulb  of   Q    contains    slightly  moist  cotton-wool. 
The  object  of  the  moist  cotton-wool  is  to  introduce  the  gas  into 
the  absorption  apparatus  with  the  same  amount  of  moisture  it  has 
when  it  leaves  it.     The  drying  property  of  H2SO4  being  greater  Different 
than  that  of  chloride  of  calcium,  without  the  interposition  of  the     properties 


slightly  moist   cotton-wool   the  gas  would  enter  the  absorption 
apparatus  with  less  moisture  than  it  would  have  on  leaving  it,     CaCl2' 
and  the  increase  of  weight  would  be  less  than  the  amount  due  to 
the  CO2  absorbed.     The  Liebig  bulb  and  the  U-tube  R  form  the 
absorption  apparatus,  and  S  the  safety-tube.     Weigh  out  into  A  I    Details 

of  the 

gramme  of  pig-iron,  spiegel,  or  ferro-manganese,  or  3  grammes  of     method. 

steel  or  iron  ;  fit  in  tightly  the  rubber  stopper  carrying  the  bulb- 

tube  B,  and  attach  the  other  tubes  and  the  weighed  absorption 

apparatus  as  described  above.     Close  the  glass  stopcock  C,  and 

draw  a  few  bubbles  through  the  potash-bulb  by  applying  suction 

at  the  end  of  the  safety-tube.     Allow  the  solution  in  the  potash-  Testing  the 

tightness 

bulb   to  recede,  and  see  that  it  maintains   its   level   for   several     Ofthe 
minutes,  to    insure   the   tightness    of  all    the   joints.      Introduce 
through  the  bulb-tube   10  or   15   c.c.  of  a  saturated  solution  of 
chromic  acid,  and  then  100  c.c.  of  strong  H2SO4  which  has  been 
heated  to  boiling  with  a  little  chromic  acid,  cooled,  and  allowed 


THE   CHEMICAL   ANALYSIS    OF  IRON. 


ANAL  YSIS   OF  IRON  AND   STEEL.  l  l  5 

to  stand  over  crystals  of  chromic  acid  to  become  saturated.  The 
H2SO4  should  be  run  in  very  carefully,  to  cover  the  chromic  acid 
already  at  the  bottom  of  the  flask.  Now  introduce  in  the  same 
way  50  c.c.  of  H2SO4,  i.io  sp.  gr.,  which  will  float  on  the  top  of 
the  concentrated  acid.  Close  the  stopcock  C,  and  heat  the  flask 
gradually  almost  to  the  boiling-point  of  the  solution.  When  no 
more  gas  is  given  off,  attach  the  purifying  apparatus,  open  the 
stopcock  C,  and  start  a  current  of  air  through  the  apparatus  by 
means  of  the  bottles  L,  L.  Lower  the  light  under  A  gradually, 
finally  extinguish  it,  and,  after  passing  2  litres  of  air  through  the 
apparatus,  detach,  and  weigh  the  absorption  apparatus,  with  the 
precautions  mentioned  on  page  119.  The  increase  of  weight  is 
the  weight  of  the  CO2,  due  to  the  carbon  in  the  sample :  it  con- 
tains 27.27  per  cent,  carbon. 

B.    1.    Volatilization  of   the    Iron   in   a    Current  of  Chlorine, 
and  Subsequent  Combustion  of  the  Carbon. 

Weigh  out  i  gramme  of  pig-iron  or  3  grammes  of  steel  into 
a  porcelain  boat  about  3  inches  (75  mm.)  long,  and  treat  it  ex- 
actly as  described  on  page  65  et  seq.     The  boat  when  withdrawn 
from  the  tube  .contains  the  carbon,  slag,  and  oxides,  and  nearly 
all    of   the   non-volatile   chlorides,   such   as    MnCl2.      When   the 
sample   contains    much  manganese,  it   is    necessary  to  treat  the 
residue  in  the  boat  with  cold  water,  filter  it  on  a  small  plug  of 
ignited  asbestos,  return  it  to  the  boat,  and  dry  it  before  burning 
it  off.     As  this  adds  very  considerably  to  the  time  required  for  the  This  method 
determination,  it  is  best  to  adopt  some  other  method  for  the  deter-     able  for 
mination  of  carbon  in  such  materials  as  spiegel  and  ferro-manga-     andletro- 
nese.      Introduce   the   boat   into   the   tube   B   of  the   apparatus,     manga' 

nese. 

Fig.   54.     This   apparatus    consists  of  a  ten-burner   combustion-  Description 

of  the 

furnace  A,  through  which  runs  the  porcelain  tube  B.     This  tube     combus- 
is  about  25   inches  (625   mm.)  long,  and   ^  inch  (18  mm.)  in-     ratus. 
ternal    diameter.      It   projects    6    inches   (150   mm.)   outside   the 
furnace  at  each  end,  and  the  sheet-iron  screens  L  prevent  the  heat 


n6  THE    CHEMICAL   ANALYSIS   OF  IRON. 

Preparation  from  reaching  the  stoppers  P  and  S.  The  tube  is  filled  for  a 
ideof  cop-  length  of  6  inches  (150  mm.),  or  from  about  the  middle  of  the 
tube  to  the  forward  end  of  the  furnace,  with  oxide  of  copper, 
which  is  best  made  by  rolling  up  tightly  a  piece  of  coarse  copper 
gauze  6  inches  (150  mm.)  long  until  it  makes  a  roll  nearly  filling 
the  bore  of  the  tube,  and  heating  it  for  an  hour  in  a  current  of 

Roil  of         oxygen.     A  piece  of  thin  sheet-silver  4  inches  long,  and  forming 

silver. 

a  roll  completely  filling  the  bore  of  the  tube,  is  placed  just  in  front 
of  the  oxide  of  copper  :  it  serves  to  absorb  any  chlorine  given 
off  during  the  combustion.*  A  roll  of  copper  gauze  2  inches 
long,  with  a  loop  in  one  end,  thoroughly  oxidized,  is  pushed  in 
after  the  boat  containing  the  carbon.  The  cylinder  O  contains 
Oxygen.  oxygen  under  pressure.  The  bottles  F,  F  serve  to  force  air 
through  the  apparatus  to  replace  the  oxygen  at  the  end  of  the 
operation.  The  stopcock  T  serves  to  regulate  the  flow  of  water, 
and  consequently  of  air.  When  all  the  water  has  run  from  the 
upper  into  the  lower  bottle,  it  is  siphoned  out  of  the  latter  and 
returned  to  the  former. 


Purifying  jhe  purifying  apparatus  M  and  N,  for  oxygen  and  air  respec- 

apparatus 

for  oxygen  tively,  consist  of  Liebig  potash-bulbs  filled  with  caustic  potassa, 
1.27  sp.  gr.,  and  U-tubes,  the  sides  next  the  potash-bulbs  filled 
with  dry  pumice,  and  the  other  sides  with  chloride  of  calcium. 
The  glass  stopcocks  Q  and  R  shut  off  the  purifying  apparatus  on 
their  respective  sides  when  the  oxygen  or  air  is  passing  through 
the  other  set.  The  T-tube  D  connects  the  two  sets  of  apparatus, 
the  third  limb  passing  through  the  glass  in  the  side  of  the  hood, 
and  connecting  by  means  of  the  bent  glass-tubes  with  the  rubber 
stopper  P,  which  fits  in  the  porcelain,  tube  B.  All  the  connections 
are  made  with  glass  tubes  joined  together  by  rubber  tubing,  the 
ends  of  the  glass  tubing  being  brought  close  together  inside  the 
rubber.  This  is  to  avoid  carrying  the  oxygen  or  air  through  rub- 


*  This  roll  of  silver  must  be  occasionally  removed  and  ignited  in  a  current  of 
hydrogen  to  remove  the  chlorine. 


ANAL  YSIS   OF  IRON  AND   STEEL. 


117 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


Danger  of 
using  rub- 
ber tubes. 

Drying  and 
purifying 
apparatus 
for  CO2. 

Asbestos 
stopper. 


Absorption 
apparatus. 


Safety-guard 
tube. 


her  tubing,  which  gives  off  volatile  hydrocarbons.  The  Marchand 
U-tube  G  contains  pumice  saturated  with  anhydrous  sulphate  of 
copper  to  absorb  any  HC1  which  may  be  evolved  during  the  com- 
bustion. It  is  joined  to  the  tube  B  by  a  rubber  stopper  or  by 
an  asbestos  stopper,*  made  by  pressing  wet  fibrous  asbestos  into  a 
mould  of  the  proper  shape.  When  sufficient  pressure  is  applied 
in  making  the  stopper  it  becomes  very  hard.  When  dry  it  can  be 
bored  easily,  and  makes  an  excellent  stopper  for  this  purpose. 
The  U-tube  H  contains  granulated  dried  chloride  of  calcium.f 
The  absorption  apparatus  consists  of  the  Liebig  bulb  I  and  the 
drying-tube  J.  I  contains  caustic  potash,  1.27  sp.  gr.  It  is  filled 
by  attaching  a  short  piece  of  rubber  tubing  to  one  end  and  apply- 
ing suction  to  it,  the  other  end  being  immersed  in  the  potassa 
solution,  which  has  been  poured  into  a  capsule.  The  end  must 
be  wiped  dry  with  a  little  filter-paper,  and  the  inside  of  the  tube 
dried  in  the  same  way.  When  filled,  the  bulb  should  contain  the 
solution  as  shown  in  Fig.  55.  When  attached  to  the  apparatus, 

the  gas  passes  first  into  the  large  bulb, 
and,  the  bulbs  being  inclined,  the  gas 
bubbles  through  the  solution  in  the  three 
bottom  bulbs.  It  is  fitted  with  a  loop  of 
platinum  wire,  as  shown  in  Fig.  55.  The 
drying-tube  J  contains  fused  chloride  of 
calcium.  The  small  bulb  a,  Fig.  54,  con- 
tains a  plug  of  cotton-wool,  and  another 
plug  of  the  same  material  is  inserted  after 
the  chloride  of  calcium  at  b.  K  is  a 
safety-guard  tube,  to  prevent  moisture 
from  getting  into  the  tube  J  during  the  combustion.  The  short 
rubber  tube  V  is  used  to  draw  a  little  air  through  to  test  the 
tightness  of  the  joints.  All  the  stoppers  in  the  various  U-tubes 
and  drying-tubes  are  of  rubber.  The  copper  rod  C  is  used  to 


FIG.  55. 


J.  F.  White,  Amer.  Chem.  Jour.,  iii.  151. 


t  See  page  45. 


ANALYSIS   OF  IRON  AND   STEEL.  IIC; 

introduce  the  boats,  etc.,  into  the  tube  B,  running  the  crooked  end 
through  the  hole  W  in  the  glass  side  of  the  hood.  When  not 
attached  to  the  apparatus,  the  ends  of  the  potash-bulb  I  and  dry- 
ing-tube J  are  closed  by  little  caps  of  rubber  tubing  (Fig.  55)  made 
like  the  tips  for  "policemen."*  It  is  very  necessary  in  filling  the  Precautions 
potash-bulb  to  avoid  getting  any  of  the  solution  on  the  outside 


of  the  bulb,  and  it  is  well  to  see  that  both  the  bulb-tube  and  the 
drying-tube  are  perfectly  clean.     Wipe  off  the  potash-bulb  and     Paratus- 
drying-tube  with  a  piece  of  linen,  not  silk  (a  clean  linen  handker- 
chief that  does  not  leave  lint  on  the  glass  is  very  good  for  this 
purpose),  and  place  them  on  the  balance.     Allow  them  to  remain 
about  twenty  minutes  to  get  the  exact  temperature  of  the  balance, > 
then  remove  the  rubber  caps  for  an  instant  to  equalize  the  pressure 
inside  and  outside  the  bulb  and  tube,  allow  them  to  remain  five 
minutes  to  recover  from  the  momentary  contact  with  the  hands, 
and  weigh.     Attach   the   absorption   apparatus  as  shown    in  the  Details  of 
sketch,   Fig.    54,  insert  the  boat   in   the  tube  by  means  of  the 
rod  C,  pushing  it  up  against  the  oxide  of  copper,  insert  the  short 
roll  of  oxidized  gauze  as  far  as  the  inside  of  the  screen  L,  and 
close  the  tube  with  the  stopper  P.     Shut  the  stopcocks  R  and  Q, 
and,  by  applying,  suction  at  V,  draw  a  few  bubbles  through  the 
potash-bulb  I.     When  the   liquid  recedes  in    the   potash-bulb,  it 
should  keep  its  level  for  a  few  minutes ;  if  it  does  not,  there  is  a 
leak  in  some  of  the  connections,  which  must  be  discovered  and 
stopped  before  proceeding  with  the  combustion.      When  every- 
thing is  tight,  open  R  and  start  a  slow  current  of  oxygen  through 
the  apparatus.     Light  the   two  forward  burners  of  the  furnace, 
turning  them  low  to  heat  the  oxidized  copper  gauze,  raise  the 
heat  gradually  until  the  tube  appears  red,  and  then  light  the  last 
burner  to  heat  the  short  roll  of  oxidized  copper  gauze.     As  soon 
as  this  end  of  the  tube  is  hot,  light  the  third  burner  from  the 
forward   end,   and  a  few  minutes  afterwards  the   fourth   burner, 

*  See  page  25. 


120 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


When 

making 
a  num- 
ber of 
combus- 
tions. 


Necessity 
for  renew- 
ing KHO 
solution 
frequently. 

Condition 
in  which 
apparatus 
is  kept 
when  not 
in  use. 


which  is  directly  under  the  forward  end  of  the  boat.  Light 
each  burner  in  succession  from  this  one  until  all  are  lighted 
and  turned  high  enough  to  heat  the  tube  red-hot.  Allow  them 
to  burn  for  fifteen  minutes,  then  shut  off  the  oxygen,  close  R, 
open  Q,  and  by  means  of  the  stopcock  T  start  a  current  of  air 
through  the  apparatus.  By  means  of  the  gas-cock  X  lower  all 
the  lights  of  the  furnace  together  very  slowly,  to  avoid  cracking 
the  tube,  and  finally  turn  them  out.  About  I  litre  of  air  should 
run  through  at  the  rate  of  about  3  bubbles  a  second;  this  will 
about  half  empty  the  upper  bottle  L.  Close  T  and  Q,  detach 
the  absorption  apparatus,  close  the  ends  of  I  and  J  with  the  little 
rubber  caps,  and,  after  wiping  the  bulb  and  tube  gently  with 
the  linen  handkerchief  to  remove  any  moisture  caused  by  the 
handling,  place  them  on  the  balance.  Weigh  with  the  same 
precautions  as  before ;  the  increase  in  weight  is  CO2,  which  con- 
tains 27.27  per  cent,  carbon.  When  several  combustions  are  to 
be  made  in  succession,  as  soon  as  the  absorption  apparatus  is  de- 
tached as  directed  above,  remove  the  boat  from  the  tube,  replace 
it  with  another  containing  a  second  sample,  attach  a  second  ab- 
sorption apparatus  which  has  just  been  weighed,  and  proceed 
with  the  combustion.  While  the  second  combustion  is  in  prog- 
ress, the  first  absorption  apparatus  may  be  weighed,  and  the 
weight  then  obtained  can  be  used  for  the  first  weight  of  the 
absorption  apparatus  for  a  third  combustion.  Before  the  absorp- 
tion apparatus  shall  have  increased  .5  gramme  in  weight  from  the 
original  weighing,  the  potash-bulb  must  be  emptied  and  refilled 
with  a  fresh  solution.  When  the  final  combustion  for  the  day  is 
finished,  place  a  piece  of  glass  rod  in  the  open  end  of  the  con- 
nection of  H,  remove  the  boat  from  the  tube  B,  replace  the  short 
roll  of  oxidized  copper  gauze  in  the  tube,  insert  the  stopper  P,  but 
not  tightly,  open  R  and  Q,  and  loosen  the  stopper  X  in  the  bottle 
F.  Place  pieces  of  glass  rod  in  the  ends  of  the  safety-tube  K,  to 
prevent  access  of  moisture.  Whenever  the  apparatus  has  been  out 
of  use  for  a  day,  before  making  a  combustion  or  set  of  combustions 


ANALYSIS   OF  IRON  AND   STEEL.  I2I 

remove  the  piece  of  glass  rod  from  the  forward  end  of  the  U-tube  Tube  to  be 
H,  insert  in  its  place  a  piece  of  glass  tubing  drawn  out  at  the  for-     bdbre 
ward  end  to  a  small  orifice,  start  a  current  of  oxygen  through  the 
apparatus,  light  the  burners  in  the  furnace,  raising  the  heat  very 
gradually,  keep  the  tube  at  a  red  heat  fifteen  minutes,  turn  off  the 
oxygen,  start  the  air,  lower  the  burners  gradually,  and  pass  a  litre 
of  air  through  the  apparatus.     It  will  then  be  ready  for  the  com-  Good  results 

cannot  be 

bustion.     In  very  damp   weather  it  is  almost   impossible  to  get  obtained 

good    results,   the    condensation   of   moisture    on   the   absorption  dam*^ 

apparatus   rendering   the  weighing  extemely  difficult  even  when  Cither 
the  utmost  care  is  used. 

2.    Volatilization  of   the  Iron  in  a  Current  of   Hydrochloric 
Acid  Gas,   and  Subsequent  Combustion  of  the  Carbon. 

The  process  is  exactly  the  same  in  this  method  as  in  that  just 
described,  a  current  of  hydrochloric  acid  gas  being  substituted 
for  one  of  chlorine.  The  apparatus  for  generating  this  gas  is  the  Apparatus 

for  gener- 

same  as  the  one  used  for  chlorine,  common  rock-salt  in  pieces 
about  as  large  as  a  filbert  being  substituted  for  binoxide  of  man- 
ganese, and  sulphuric  acid,  diluted  with  two-thirds  its  bulk  of 
water,  for  hydrochloric  acid. 


C.  1.  Solution  in  Double  Chloride  of  Copper  and  Ammonium, 
Filtration,  and  Weighing  or  Combustion  of  the  Residue. 

Weigh  I  gramme  of  pig-iron,  Spiegel,  or  ferro-manganese  into 
a  No.  2  Griffin's  beaker,  and  add  100  c.c.  of  saturated  neutral 
solution  of  the  double  chloride  of  copper  and  ammonium.*  For 
steel  or  puddled  iron,  weigh  3  grammes  into  a  No.  3  beaker,  and 
add  250  c.c.  of  the  double  chloride  of  copper  and  ammonium 
solution.  Stir  the  solution  constantly  with  a  glass  rod  for  some 
minutes  at  the  ordinary  temperature.  The  more  it  is  stirred  the 
more  rapid  will  be  the  solution  of  the  iron  and  of  the  precipitated 

*  See  page  47. 
9 


122 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Solution 
of  the 
sample. 


Filtering  on 
perforated 
platinum 
boat. 


FIG.  56. 


copper.  The  beaker,  carefully  covered,  may  now  be  placed  on 
the  top  of  the  air-bath  or  on  a  cool  part  of  the  sand-bath,  but  the 
solution  should  never  be  heated  hotter  than  60°  or  70°  C,  and  it 
should  be  stirred  as  often  as  practicable.  The  reactions  occurring 
may  be  considered  as  Fe+ CuCl2=FeCl24-  Cu  and  Cu-f  CuCl2= 
2CuCl.  The  part  taken  by  the  chloride  of  ammonium  does  not 
seem  very  clear,  but  the  fact  remains  that  the  precipitated  copper 
is  much  more  soluble  in  the  double  chloride  of  copper  of  am- 
monium than  in  any  other  menstruum.  There  is  always  a  slight 
oxidation  of  the  ferrous  chloride,  and,  the  solution  being  very 
neutral,  some  ferric  oxide  or  basic  ferric  chloride  separates  out 
in  the  form  of  a  scum  on  the  surface  of  the  liquid.  When  the 
precipitated  copper  is  all,  or  very  nearly  all,  dissolved,  which  is 
usually  the  case  in  half  an  hour  after  the  solution  of  double  chlo- 
ride of  copper  and  ammonium  is  added  to  the  drillings,  pour 

about  10  c.c.  of  hot 
dilute  HC1  (i  part  acid 
to  5  parts  water)  into 
the  beaker  so  that  it 
may  run  over  the  sur- 
face of  the  liquid.  This 
will  quickly  dissolve  the 
scum,  and,  as  soon  as 
the  surface  of  the  solu- 


tion clears,  stir  it  up, 
and  let  the  beaker  stand 
for  a  few  minutes  to  al- 
low the  carbonaceous 
matter  to  settle.  The 
best  form  of  filtering- 
apparatus  is  shown  in  the  annexed  sketches.  It  consists  of  the 
perforated  platinum  boat  (Fig.  56),  which  fits  in  the  platinum 
holder.  To  prepare  the  boat  for  use,  place  it  in  the  holder, 
as  shown  in  Fig.  57,  attach  the  pump,  but  do  not  start  it. 


ANAL  YSIS   OF  IRON  AND   STEEL. 


123 


Fill  the  boat  with   prepared  asbestos*  suspended  in  water,  pour 
enough  around  the  outside  of  the  boat  to  fill  the  space  a,  Fig.  57,  Method  of 
and  start  the  filter-pump.     Continue  pouring  the  suspended  as- 
bestos into  the  space  a,  Fig.  57,  until  enough  is  drawn  into  the 

FIG.  57. 


joint  to  make  a  good  packing.  By  pressing  it  in  all  round  with  a 
spatula  the  joint  may  be  made  very  tight  Pour  enough  of  the 
suspended  asbestos  into  the  boat  to  make  a  good,  thick  felt,  and 
press  it  down  firmly  all  over  the  bottom  of  the  boat  with  some- 
thing like  the  square  end  of  a  lead-pencil,  to  make  it  compact. 
Detach  the  pump,  remove  the  boat  from  the  holder  carefully  so 

*  See  page  20. 


124 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


as  to  leave  the  packing  on  the  sides  of  the  holder,  and  move  it 
up  with  the  end  of  a  spatula,  so  that  it  will  remain  as  shown  in 
Fig.  56.  Place  another  boat  in  the  holder,  press  the  packing  into 
the  joint  a,  Fig.  57,  with  the  end  of  a  spatula,  fill  the  boat  with 
suspended  asbestos,  and  start  the  pump.  If  necessary,  pour  a 
little  of  the  finer  suspended  asbestos  fibre  into  the  joint  to  make 
it  perfectly  tight,  and  prepare  the  felt  in  the  boat  as  before.  Dry 
the  boats,  and  ignite  them  in  the  combustion-tube,  two  at  a  time, 
in  a  current  of  oxygen.  Fit  one  of  these  prepared  boats  in  the 
holder,  press  the  packing  into  the  joint  as  before,  first  moisten- 
ing it  slightly  if  it  has  become  dry,  start  the  pump,  and  pour 
into  the  boat  enough  suspended  asbestos,  which  has  been  ignited 
in  oxygen,  to  form  a  thin  film  on  the  top  of  the  felt.  This  film 
will  hold  the  silica,  phosphate  of  iron,  etc.,  from  the  carbonaceous 
residue,  and,  after  the  combustion,  will  usually  turn  up  at  the 
edges,  so  that  it  can  be  readily  detached  from  the  main  felt,  leav- 
ing the  boat  ready  for  another  filtration. 

Filtering  on  The  boat  being  thus  prepared,  pour  into  it  the  solution  of  the 

thaer^e~  iron  or  steel,  guiding  the  stream  by  a  small  glass  rod  held  against 
boat.  the  tjp  Of  t^e  beaker.  The  solution,  if  the  joint  a,  Fig.  57,  is 
tight,  and  the  pump  works  well,  will  usually  run  through  the  felt 
as  rapidly  as  it  can  be  poured  into  the  boat.  When  the  super- 
natant fluid  has  all  run  through,  transfer  the  carbonaceous  matter 
to  the  boat  by  a  fine  stream  of  cold  water  from  a  washing-flask. 
Pour  into  the  beaker  about  10  c.c.  of  the  hydrochloric  acid  used 
to  dissolve  the  scum  on  the  top  of  the  solution,  run  it  all  around 
the  inside  of  the  beaker  by  means  of  the  rod  to  dissolve  any  little 
basic  salt  of  iron,  wash  off  the  glass  rod  and  wash  down  the  sides 
of  the  beaker  with  a  jet  of  water,  and  decant  the  acid  into  the 
boat,  filling  the  boat  almost  up  to  the  edge.  Wash  the  carbona- 
ceous matter  in  the  boat  thoroughly  with  cold  water  by  filling 
the  boat  from  the  beaker  and  allowing  it  to  suck  through  dry, 
but  do  not  attempt  to  throw  a  jet  of  water  into  the  boat  from  the 
washing-flask,  as  it  will  be  almost  certain  to  throw  some  of  the 


ANAL  YSIS   OF  IRON  AND   STEEL. 


125 


of  different 
samples. 


FIG.  58. 


carbonaceous  matter  from  the  boat  or  cause  it  to  crawl  over  the 
side.     In  decanting  the  water  from  the  beaker,  the  lip  must  not 
be  allowed  to  touch  the  surface  of  the  liquid  in  the  boat,  as  a 
film  of  carbonaceous  matter  will  run  up  the  inside  of  the  beaker. 
Pour  a  little  dilute  acid  into  the  joint  between  the  boat  and  holder, 
allow  it  to  suck  through  the  packing,  and  wash  it  several  times 
with  cold  water.     The  carbonaceous   matter  from  pig-iron,  pud-  Differences 
died  iron,  Spiegel,  ferro-manganese,  and  ingot  steel  usually  washes     filtration0 
like  sand,  but  that  from  steel  which  has  been  hardened,  tempered, 
hammered,  or  rolled   is  apt  to  be  more  or  less  gummy,  stopping 
the  filter  and  rendering  the  filtration  and  washing  prolonged  and 
tedious.     It  is  also  apt  to  adhere  more  or  less  to  the  sides  of  the 
beaker,  and  must  be  wiped  off  by  a  little  wad  of  ignited  fibrous 
asbestos,  held   in  a   pair  of  platinum-pointed  forceps  like  those 
shown  in  Fig.  58.     This  wad  is  then  placed  in  the  boat.     When 
the    carbonaceous    matter    is 
thoroughly     washed     and 
sucked  dry,  detach  the  pump, 
remove  the  boat  from  the  holder,  wipe  it  off  carefully  with  a  piece 
of  silk,  place  it  in  a  dish  covered  with  a  watch-glass,  and  dry  it 
in  a  water-bath  or  in  an  air-bath  at   100°  C.     When  dry,  insert 
the  boat  in  the  tube  (Fig.  54),  and  burn  off  the  carbon  as  directed 
on  page   119.     Instead  of  the  porcelain  tube,  a  platinum  tube  of  Platinum 
the  dimensions  shown  in  Fig.  60  may  be  used  to  very  great  advan-     tk>n-tute. 
tage.     The  rear  end  has  a  ground  joint  (Fig.  59),  which  may  be 
made  perfectly  air-tight.     The  tube  has 
a  strengthening  band  of  German  silver  at 
B,  Fig.  60,  and  the  part  P,  which  is  of 
phosphor-bronze,  is  ground  in.     To  pre- 
vent the  tube  from  sagging  when  it  is 

hot,  the  rear  end  is  supported  at  P,  Fig.  60,  by  a  wire  from  the 
top  of  the  hood.  A  piece  of  platinum  gauze  6  inches  long  (150 
mm.),  rolled  up  rather  loosely,  fills  the  forward  end  of  the  tube, 
and  a  similar  roll  2  inches  long,  with  a  loop,  is  pushed  in  after  the 


126 


THE   CHEMICAL  ANALYSIS  OF  IRON. 


ANALYSIS  OF  IRON  AND   STEEL. 

boat,  the  rear  end  coming  just  forward  of  the  screen  L.  The 
limb  of  the  U-tube  G  nearest  the  platinum  tube  contains  anhy- 
drous sulphate  of  copper  in  pumice,  and  the  forward  limb,  bright, 
clean  copper  turnings,  separated  from  the  pumice  by  a  plug  of 
fibrous  asbestos.  A  plug  of  cotton-wool  is  placed  between  the 
copper  turnings  and  the  rubber  stopper.  When  the  apparatus 
is  not  in  use,  G  and  H  should  always  be  detached  from  the  tube 
B  and  the  ends  closed  with  pieces  of  glass  rod.  Before  making  Necessity 
a  combustion,  or  series  of  combustions,  the  tube  should  be  well 
burned  out  by  heating  it  to  redness  and  passing  a  current  of 
oxygen  through  the  apparatus,  heating  the  small  tube  S  red-hot  combus- 
at  the  same  time  by  means  of  a  small  blast-lamp  or  Bunsen 
burner.  During  this  operation  fumes  of  sulphuric  acid  issue  from 
the  end  of  S,  and  usually,  when  the  flame  of  the  lamp  is  carried 
out  to  this  point,  it  is  colored  green,  showing  that  a  small  amount 
of  copper  salt  is  also  volatilized.  In  making  a  combustion  the 
platinum  should  not  be  heated  above  a  low  red,  as  at  a  high  tem- 
perature platinum  becomes  permeable  by  CO2.  The  burners  in 
the  furnace  should  be  lighted  in  the  order  directed  on  page  119, 
and,  after  they  are  all  lighted,  ten  minutes  are  ample  to  burn  off 
the  carbonaceous  matter  in  the  boat.  From  the  time  of  putting 
in  the  boat,  fifty  minutes  are  ample  for  finishing  the  combustion, 
including  the  displacement  of  the  oxygen  by  air.  The  time  re- 
quired when  using  a  porcelain  tube  is  somewhat  longer,  owing  to 
the  danger  incurred  of  cracking  the  tube  if  the  heat  is  increased 
or  diminished  too  rapidly.  A  platinum  tube  shorter  than  the  one 
here  figured  is  not  to  be  recommended,  as  it  cannot  contain 
enough  oxygen  to  burn  the  carbon  to  CO2,  and  a  consequent  loss 
is  often  unavoidable.  Duplicate  results  by  this  method  should 
rarely  vary  more  than  .005  of  a  per  cent,  carbon.  When  using 
3  grammes  of  the  sample,  the  percentage  of  carbon  is  obtained 
by  dividing  the  weight  of  CO2  by  n  and  multiplying  by  100. 

Instead  of  the  perforated  boat  and  holder  described  above,  the 
carbonaceous  residue  may  be  filtered  in  a  small  platinum  tube 


128 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Glass  filter- 
ing-tube. 


fitting  inside  the  combustion-tube.      It  is  made  as  represented  in 
Fig.  61.     The  small  perforated  disk  of  platinum  rests  on  a  seat 
FIG.  61.     m  tne  tube  as  shown  in  the  sketch.     The  felt  in  the  disk 
is  prepared  in  the  same  way  as  directed  for  the  boat,  and, 
after  drying  the  carbonaceous  residue,  the  disk  is  moved 
upward  in  the  filtering-tube  before  inserting  the  latter  in 
the  combustion-tube,  to  allow  the  gas  to  pass  through 
the  filtering-tube  during  the  combustion.     The  boat  has 
several  advantages  over  the  filtering-tube,  the  principal 
one  being  that  the  boat  has  a  much  larger  filtering-surface,  and, 
besides,  there  is  no  danger  of  the  felt  being  disturbed  during  the 
filtering,  while  the  disk  in  the  tube  may  be  loosened  in  its  seat 
and  allow  some  of  the  carbonaceous   matter  to  pass   around  it. 
FlG  62  If  the  boats  when  not  in  use  are  kept  carefully 

covered,  the  same  felts  may  be  used  for  a  large 
number  of  filtrations  ;  but  occasionally  they  be- 
come    clogged,     and 
then    it    is    better    to 
renew  them. 

Instead  of  either 
of  these  forms  of  filter- 
ing-apparatus, a  sim- 
ple glass  tube,  as  rep- 
resented in  Fig.  62, 
may  be  used.  The 
closely-coiled  spiral  of 
platinum  wire  fits  in 
the  tube  as  shown  in 
the  sketch.  On  this  is 
placed  a  rather  thick 
layer  of  ignited  long- 
fibre  asbestos,  and 

ignited  asbestos  suspended  in   water  is  poured  over  it  to  make 
a  solid  felt.     The  tube  may  be  used  in  a  stand,  as  represented  in 


FIG.  63, 


ANAL  YSIS   OF  IRON  AND   STEEL. 

Fig.  63,  or  it  may  be  used  with  the  filter-pump  under  very  gentle 
pressure.  Filter  and  wash  the  carbonaceous  matter,  and  while  still 
moist  transfer  it  to  the  boat  (Fig.  64)  by  opening  out  the  sides  of 

FIG.  64. 


129 


Boats  of 
platinum- 
foil. 


the  boat,  inverting  the  tube  over  it,  and  allowing  the  felt  and  spiral 
to  slide  out  of  the  tube.  Wipe  off  any  carbonaceous  matter  that 
may  remain  on  the  sides  of  the  tube,  or  that  may  have  ad- 
hered to  the  spiral  in  removing  it,  with  little  wads  of  fibrous 
asbestos  held  in  the  forceps  (Fig.  58).  Place  these  wads  in  the 
boat,  bend  the  sides  of  the  latter  into  their  proper  shape,  dry  the 
boat  and  contents  at  100°  C.,  insert  the  boat  in  the  porcelain  or 
platinum  tube,  and  burn  off  the  carbonaceous  matter  as  before 
directed.  This  boat  is  made  by  cutting  a  piece  of  platinum-foil  in 


FIG.  65. 


the  shape  shown  in  Fig.  65,  and  bending  it  up  over  a  brass  former 
into  the  shape  shown  in  Fig.  64. 

Instead  of  burning  the  carbonaceous  matter  in  a  current  of 

Combustion 

oxygen,  it  may  be  burned  by  H2SO4  and  CrO3  in  the  arrange-     of  the 
ment  shown  in   Fig.  66.     P'  is  an  empty  U-tube,  O  is   a  tube 


130 


THE   CHEMICAL  ANALYSIS  OF  IRON, 


ANALYSIS   OF  IRON  AND   STEEL.  131 

containing  sulphate  of  silver  dissolved  in   strong  H2SO4,  P  con-     mCrO8 

and 

tains  anhydrous  sulphate  of  copper  in  pumice,  Q  granular  dried  H2so4. 
chloride  of  calcium,*  the  Liebig  bulb  and  drying-tube  R  con- 
stitute the  absorption  apparatus,  S  is  the  safety-guard  tube,  and 
L,  L  .constitute  the  arrangement  for  passing  air  through  the 
apparatus.  The  air  is  freed  from  CO2  in  passing  through  the 
U-tube  M  filled  with  lumps  of  fused  caustic  potassa.  Transfer 
the  carbonaceous  matter  and  asbestos  to  the  flask  A,  insert 
the  stopper  carrying  the  bulb-tube  B,  close  the  stopcock  C, 
and  connect  the  apparatus  as  shown  in  Fig.  66,  including  the 
weighed  absorption  apparatus.  See  that  the  joints  are  all  tight, 
and  then  pour  into  B  10  c.c.  of  a  saturated  solution  of  chromic 
acid,  admit  it  to  the  flask  A  by  opening  the  stopcock  C,  and  then 
pour  into  B  100  c.c.  strong  H2SO4  which  has  been  heated  almost 
to  boiling  with  a  little  CrO3.  Let  this  run  into  A  slowly,  connect 
the  air-apparatus  by  the  tube  N,  and  start  a  slow  current  of  air 
through.  Light  a  very  low  light  under  A,  and  increase  it  grad- 
ually until  the  liquid  is  heated  to  the  boiling-point.  Gradually 
lower  the  light  while  the  current  of  air  continues  to  pass,  and 
when  about  I  litre  of  air  has  passed  through  the  apparatus  after 
the  light  is  extinguished,  detach  and  weigh  the  absorption  appa- 
ratus, with  the  precautions  mentioned  on  page  119. 

The  carbonaceous  residue  may  also  be  weighed  directly  instead  ^^^ 
of  being  burned  off.     In  this  method,  filter  on  a  Gooch  crucible  or     residue, 
on  counterpoised  filters,f  dry  at  100°  C.,  and  weigh.     Burn  off  the 
carbonaceous  matter  and  weigh  the  residue :  the  difference  between 
the  two  weights  is  carbonaceous  matter,  which  contains  about  70 
per  cent,  of  carbon  J  in  steel  or  iron  free  from  graphite.     Of  course 
this  method  of  direct  weighing  is  applicable  only  to  samples  when 
all  the  carbon  is  in  the  so-called  combined  condition. 


*  The,  bulb  of  Q  contains  a  wad  of  slightly  moistened  cotton-wool,  as  described 
on  page  113. 

f  See  page  22.  J  Amer.  Chem.  Jour.,  iii.  245. 


132  THE    CHEMICAL   ANALYSIS   OF  IRON. 

2.  Solution  in  Chloride   of   Copper    and  Chloride  of  Sodium 

or  Potassium,  Filtration,  and  Combustion  of  the  Residue 
in  Oxygen. 

As  a  solvent  this  salt  has  no  advantage  over  the  ammonium 
salt,  except  that  it  contains  no  volatile  constituent  like  chloride  of 
ammonium,  which,  when  the  carbonaceous  residue  is  not  properly 
washed,  may  be  carried  forward,  and,  suffering  decomposition  in 
the  red-hot  platinum  gauze  in  contact  with  oxygen,  form  some 
compound  that  would  be  absorbed  by  the  solution  of  caustic 
potassa.  On  the  contrary,  its  action  on  iron  or  steel  is  not  so 
rapid  as  that  of  the  ammonium  salt,  and  it  is  not  so  readily  ob- 
tained as  an  article  of  commerce.  Its  use,  therefore,  is  not  to  be 
recommended. 

3.  Solution   in   Chloride  of  Copper,  and  Combustion  of   the 

Residue. 

The  same  remarks  apply  to  this  reagent  as  to  the  one  just 
mentioned,  and  in  addition  it  has  the  great  disadvantage  that  it  is 
not  possible  to  get  it  so  nearly  neutral  as  the  chloride  of  copper 
and  ammonium,  so  that  there  is  always  likely  to  be  a  slight  loss  of 
carbon  through  the  evolution  of  carburetted  hydrogen. 

4.  Solution    in    Iodine    or    Bromine,    and    Combustion    with 

Chromate  of  Lead,  or  Weighing-,  of  the  Residue. 

The  determination  by  this   method,  when   iodine  is   used,   is 

carried  out  exactly  as  directed  for  the  estimation  of  "  Slag  and 

Oxides,"  page  70,  the  residue  being  filtered  on  asbestos,  dried,  and 

burned  with  chromate  of  lead  or  oxide  of  copper,  as  directed  in 

weighing       A.  2,  page   109  et  seq.     The  residue  may  also  be   filtered   on   a 

dueeres        counterpoised  filter*  or  Gooch  crucible,  washed,  dried  at  100°  C., 

weighed,  the   carbonaceous    matter   burned   off,  and  the  residue 

weighed.     The  difference  between  the  weights  is  the  amount  of 

*  See  page  22. 


ANALYSIS   OF  IRON  AND  STEEL.  !3 

carbonaceous  matter,  which  contains,  according  to  Eggertz,*  59 
per  cent,  of  carbon.  It  also  contains  about  16  per  cent,  of 
iodine,  so  that  the  residue  cannot  be  burned  in  a  current  of 
oxygen,  nor  with  CrO3  and  H2SO4.  If  bromine  is  used  instead 
of  iodine,  great  care  must  be  taken  in  adding  the  bromine,  10  c.c. 
bromine  for  5  grammes  of  iron  or  steel,  as  the  action  is  very 
violent,  and  unless  the  bromine  is  added  very  slowly  and  the 
solution  kept  as  near  o°  C.  as  possible,  there  will  be  oxidation,  and, 
consequently,  loss  of  carbon.  The  details  of  the  method  when 
bromine  is  used  are  otherwise  the  same  as  when  iodine  is  the 
solvent. 

5.    Solution  by   Fused    Chloride   of   Silver,   and   Combustion 

of  the  Residue. 

Fuse  in  a  porcelain  crucible  20  grammes  of  chloride  of  silver,  Details 
and  see  that  the  button  when  cold  has  a  smooth,  flat  surface  on  method, 
top.  Place  the  button  in  a  porcelain  dish  about  6  inches  (15  cm.) 
in  diameter,  and  pour  on  the  button  3  grammes  of  drillings.  Add 
300  c.c.  cold  distilled  water  containing  2  drops  of  JHC1,  place  the 
dish  on  a  ground-glass  plate,  and  cover  it  with  a  bell-glass  to 
exclude  the  air  during  the  time  occupied  in  dissolving  the  sample. 
It  is  not  necessary  that  the  sample  should  be  in  drillings,  as  a 
single  piece  will  be  dissolved  in  this  way.  The  chloride  of  silver 
should  weigh  at  least  6  times  as  much  as  the  sample  of  iron  or 
steel.  The  reaction  is  a  simple  substitution,  Fe-f-  2 AgCl  =  FeCl2 
-|-2Ag,  by  galvanic  action,  but  secondary  reactions  occur,  including 
the  decomposition  of  water,  both  hydrogen  and  oxygen  being 
taken  up  by  the  carbon  at  the  moment  of  its  liberation.  A  slight 
excess  of  oxygen  over  the  amount  necessary  to  form  water  with 
the  hydrogen  is  taken  up  and  a  little  hydrogen  is  liberated. 
There  is  a  tendency,  of  course,  for  the  ferrous  chloride  when 
formed  to  oxidize,  consequently  the  air  must  be  excluded.  The 
decomposition  requires  several  days,  as  many  as  ten  if  the  sample 

*  Percy,  Iron  and  Steel,  page  891. 


THE   CHEMICAL  ANALYSIS   OF  IRON. 

of  steel  or  iron  is  in  a  single  piece  and  not  very  thin.  The 
metallic  silver  is  quite  cohesive,  and  is  readily  separated  from  the 
carbonaceous  residue.  When  the  action  is  finished,  remove  the 
mass  of  silver,  washing  off  any  of  the  carbonaceous  matter  ad- 
hering to  it,  add  a  little  HC1  to  dissolve  any  ferric  oxide  which 
may  have  formed,  filter  off,  and  burn  the  carbonaceous  matter  by 
one  of  the  methods  previously  described. 

6.  Solution  of  the  Iron  in  Sulphate  of  Copper,  Filtration, 
and  Combustion  of  the  Residue  in  a  Boat  in  a  Current 
of  Oxygen. 

Weigh  3  grammes  of  steel  into  a  No.  3  beaker,  and  add  150 
sulphate  c.c.  of  solution  of  sulphate  of  copper,  made  by  dissolving  200 
grammes  of  the  copper  salt  in  water,  adding  a  dilute  solution  of 
caustic  soda  until  a  slight  permanent  precipitate  appears,  allowing 
it  to  settle,  filtering  through  asbestos,  and  diluting  to  I  litre.  For 
pig-iron,  Spiegel,  and  ferro-manganese,  use  I  gramme,  and  50  c.c. 
of  sulphate  of  copper  solution.  Heat  the  solution  gently,  and  stir 
well  until  decomposition  is  complete.  Filter  in  a  glass  filtering- 
tube  on  asbestos,  as  described  on  page  128.  Wash  well  with 
water,  transfer  to  a  boat,  as  directed  on  page  129,  dry,  and  burn 
in  a  porcelain  tube,  as  directed  for  A.  i,  page  109.  The  results  are 
apt  to  be  a  little  low,  owing  to  the  difficulty  of  thoroughly  oxi- 
dizing the  mass  of  copper  mixed  with  the  carbonaceous  matter.* 
Instead  of  filtering  off  the  mass  of  copper,  carbonaceous  matter, 
etc.,  decant  the  clear  supernatant  fluid  through  the  filtering-tube, 
wash  several  times  by  decantation,  and  then  dissolve  the  copper  in 
double  chloride  of  copper  and  ammonium,  chloride  of  copper,  or 
ferric  chloride.  Filter,  wash  the  residue  with  a  little  dilute  HC1, 
and  then  with  cold  water,  transfer  to  a  boat,  and  burn  as  directed 
on  page  1 1 5  et  seq. 

*  See  report  of  the  U.  S.  Board  appointed  to  test  iron,  steel,  and  other  metals, 
vol.  i.  p.  284. 


ANALYSIS   OF  IRON  AND  STEEL. 

7.  Solution  of   the  Iron  in  Sulphate  of  Copper,  and  Oxida- 

tion of  the  Residue  by  CrO3  +  EL^SO^ 

Treat  the  sample  with  solution  of  sulphate  of  copper,  as  in  the 
method  just  described.  Allow  the  precipitated  copper  and  car- 
bonaceous matter  to  settle,  pour  off  the  clear  supernatant  liquid, 
and  transfer  the  residue  to  the  flask  A  (Fig.  66,  page  130)  by 
means  of  a  platinum  spatula  and  a  fine  jet  of  water.  The  water 
used  should  not  exceed  20  or  25  c.c.*  The  apparatus  is  that 
sketched  in  Fig.  66,  the  only  difference  being  that  the  tube  O  con- 
tains merely  a  little  strong  H2SO4.  Effect  the  combustion  exactly 
as  described  on  page  131. 

8.  Solution  of  the  Iron  in  Sulphate  of    Copper,   Filtration, 

and  Combustion  of  the  Residue,  mixed  with  Oxide  of 
Copper  in  Vacuo  under  the  Sprengel  Pump,  the  Volume 
of  CO2  being-  measured. 

Treat  1-3  grammes  of  drillings  exactly  as  described  under  C. 
6,  page  134,  filter  on  ignited  asbestos  in  a  glass  tube,  dry  the 
residue,  consisting  of  copper,  carbonaceous  matter,  and  asbestos, 
mix  it  with  about  50  grammes  of  pure  oxide  of  copper,  and 
charge  it  into  a  glass  combustion-tube,  as  directed  under  A.  2, 
page  109.  The  end  of  the  combustion-tube  should  not  be  drawn 
out  at  an  angle,  however,  but  rounded  and  thickened  in  the  flame, 
as  shown  in  Fig.  67.  When  the  residue  has  been  transferred  to 
the  tube,  soften  the  forward  end  in  F  6 

'  of  the 

the   flame,   draw    it   out,  bend   it   at    (**  °°^) 


right  angles,  and,  after  cutting  off  the 

large  end,  fuse  the  edges  of  the  small  tube.  The  combustion- 
tube  should  originally  be  about  18  inches  (450  mm.)  long,  the 
drawn-out  part  4  inches  (100  mm.)  long,  and  ^  inch  (6  mm.)  in 
diameter.  Place  the  tube  in  the  combustion-furnace,  and  attach 

*  The  borings  may  be  treated  with  the  salphate  of  copper  solution  in  the  flask  A, 
and  the  clear  liquid  drawn  off  with  a  pipette.  This  will  avoid  the  necessity  for  trans- 
ferring the  residue. 


136 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


the  Sprengel  pump,  as  shown  in  the  sketch,  Fig.  68.     The  com- 
bustion-tube is  connected  with  the  Sprengel  pump  by  the  tube  b, 
Making  the    ancj  the  joints  at  a  and  c  are  made  by  connecting  the  ends  of  the 
tubes   together  with    short   lengths    of   rather   heavy   pure    gum 


joints. 


FIG.  68. 


tubing  well  wired.  Before  the  ends  of  the  tubes  are  connected, 
a  rubber  stopper  is  forced  over  the  end  of  b  at  a,  and  another 
over  the  end  of  b  at  c.  These  stoppers  support  short  pieces  of 
glass  tubing  of  about  ^  inch  (16  mm.)  inside  diameter.  After 
the  ends  of  the  tubes  are  connected,  the  stoppers  are  pushed  up 
so  that  the  joints  are  entirely  within  the  large  tubes,  which  are 
then  filled,  the  one  at  a  with  water,  and  that  at  c  with  glycerine. 
To  the  end  of  the  pump  is  attached  a  tube,  d,  the  end  of  which 


ANALYSIS  OF  IRON  AND  STEEL. 

bends  upward;  it  rests  in  the  mercury-trough  as  shown  in  the 
sketch.  When  the  apparatus  is  properly  connected,  light  a  burner 
under  the  forward  part  of  the  combustion-tube,  which  contains 
only  oxide  of  copper,  and  start  the  pump  by  opening  carefully  the 
screw-clamp  g,  the  funnel  e  being  full  of  mercury.  Regulate  the 
flow  of  mercury  so  that  it  does  not  rise  into  the  connecting-tube  f. 
When  the  vacuum  is  complete,  the  mercury  will  fall  with  a 
clicking  sound  ;  then  close  the  screw-clamp  g,  place  over  d  a  care- 
fully calibrated  glass  tube  of  100  c.c.  capacity  graduated  in  -fa  c.c., 
filled  with  mercury,  and  heat  the  combustion-tube  gradually  to 
redness  for  its  entire  length.  When  no  more  gas  is  given  off, 
lower  all  the  burners  a  little,  start  the  pump  slowly,  and  transfer 
all  the  gas  to  the  graduated  tube.  Stop  the  pump,  transfer  the 
graduated  tube  to  a  mercury-cistern  by  means  of  a  capsule  con- 
taining mercury,  and  adjust  the  tube  so  that  the  mercury  will  be 
at  the  same  height  inside  and  outside  the  tube.  Read  the  volume 
of  the  gas,  which  is  pure  CO2,  and  also  take  the  temperature  by 
means  of  a  thermometer  hanging  near  the  tube,  and  the  height  of 
the  barometer.  As  the  carbonaceous  matter  contains  hydrogen, 
which  by  the  combustion  is  oxidized  to  H2O,  we  must  correct  the  correction  of 
volume  of  gas  obtained  for  temperature,  barometric  pressure,  and  for  press- 
tension  of  aqueous  vapor  to  reduce  it  to  the  volume  it  would 
occupy  in  the  dry  state  at  o°  C.  and  760  mm.  pressure,  the  con- 
dition  in  which  the  weight  of  a  litre  of  CO,  has  been  determined,  aqueous 

vapor. 

The  coefficient  of  expansion  of  gases  from  o°  C.  to  100°  C.  has 
been  determined  to  be  .3665;  they  expand,  therefore,  for  i°  C. 
^^.=.003665.  To  reduce  the  volume  of  a  gas  at  any  given 
temperature  to  the  volume  it  would  occupy  at  o°  C.,  we  have  the 

equation  -  -  =;tr,  in  which  a  is  the  volume  it  occupies 
.  003665) 


at  the  observed  temperature  bt  and  x  is  its  volume  at  o°  C.  The 
tension  of  aqueous  vapor,  or  the  volume  it  occupies  at  a  given 
temperature,  measured  in  mm.,  is  given  in  the  table.  Take  from 
this  table  the  tension  of  aqueous  vapor  at  the  observed  tempera- 

10 


138 


THE   CHEMICAL  ANALYSIS   OF  IRON. 


ture  and  subtract  it  from  the  height  of  barometer  observed  at  the 
same  time ;  this  gives  the  actual  pressure  under  which  the  gas  was 
at  the  moment  the  volume  was  read.  Now,  as  the  volume  of  a 
gas  is  inversely  as  the  pressure  to  which  it  is  exposed,  we  have : 
As  760  :  the  actual  pressure  : :  the  corrected  volume  at  o°  C. : 
the  actual  volume  at  760  mm.  and  o°  C.  As  I  litre  of  CO2  at 
760  mm.  bar.  and  o°  C.  weighs  1.9663  grammes,  I  c.c.  of  CO2 
under  the  same  conditions  weighs  .0019663  gramme.  Multiply 
the  actual  volume  of  CO2  obtained  above  in  c.c.  by  .0019663, 
and  the  result  is  the  weight  of  the  CO2  in  grammes. 


Description 
of  the  ap- 
paratus. 


FIG.  69. 


9.  Solution  in  Dilute  HC1  by  the  Aid  of  an  Electric  Current, 
and  Combustion  of  the  Residue. 

The  arrangement  shown  in  Fig.  69  may  be  used  in  carrying 
out  the  details  of  this  method.  It  consists  of  a  No.  3  Griffin's 
beaker,  in  which  is  a  piece  of  platinum-foil,  the  wire  from  which 
connects  with  the  negative  pole  of  the  battery ;  a  small  basket  of 
very  fine  platinum  gauze  is  supported  from  a  platinum  wire,  on 

one  end  of  which  is  a  clamp 
connecting  with  the  positive  pole 
of  the  battery.  The  battery  is 
usually  a  single  Bunsen  or  Grove 
element,  and  the  intensity  of  the 
current  should  be  regulated  by 
varying  the  distance  between  the 
foil  and  the  basket,  or  by  intro- 
ducing resistance-coils  in  the 
connections,  so  that  no  gas  is 
given  off  from  the  iron.  Hydro- 
gen, of  course,  is  given  off  abun- 
dantly from  the  surface  of  the 
foil,  and  the  iron  dissolves  in  the  acid  as  ferrous  chloride.  Weigh 
into  the  basket  from  I  to  5  grammes  of  the  sample,  which  should 
be  in  pieces  and  not  in  powder.  Suspend  the  basket  from  the 


ANALYSIS   OF  IRON  AND   STEEL. 

wire,  having  previously  connected  the  rest  of  the  apparatus  and  Details 
poured  into  the  beaker  a  mixture  of  200  c.c.  water  and  50  c.c.      method. 
HC1,  and  regulate  the  intensity  of  the  current  as  directed  above. 
By  looking  through  the  solution,  a  stream  of  colorless  ferrous 
chloride  will  be  seen  falling  to  the  bottom  of  the  beaker,  but  when 
the  current  is  too  strong  the  iron  becomes  passive,  and  chlorine  is 
given  off  at  the  positive  pole,  which  oxidizes  the  iron  and  colors 
the  descending  current  yellow  with  ferric   chloride.     When  the 
sample  is  in  a  single  piece,  the  solution  requires  eight  to  ten  hours. 
The  carbonaceous  matter  usually  retains  the  form  of  the  sample. 
When  solution  is  complete,  disconnect  the  battery,  remove  the  foil 
from  the  liquid,  wash  the  carbonaceous   matter  from  the  basket 
with  a  jet  of  cold  water,  filter  it  off,  and  determine  the  amount  of 
carbon  by  one  of  the  methods  previously  given. 

10.  Oxidation  of  the  Iron  by  Atmospheric  Air  and  Moisture, 
Solution  of  the  Ferric  Oxide  in  HC1,  Filtration,  and 
Combustion  of  the  Residue. 

This  is  the  only  method  for  the  determination  of  carbon  in 
iron  or  steel  in  which  the  carbon  is  not  liberated  in  the  presence 
of  an  acid  or  of  a  metallic  salt,  and  the  details  are  given  here 
because  the  method  may  be  useful  in  a  study  of  the  composition 
of  the  liberated  carbonaceous  matter.  Weigh  the  sample,  in  as 
finely  divided  a  condition  as  possible,  into  a  flat-bottomed  porce- 
lain dish,  moisten  it  with  water,  cover  the  dish  carefully,  and  allow 
it  to  stand  twenty-four  hours.  Add  20  or  30  c.c.  of  water,  stir  it 
well,  and  decant  the  water  and  the  iron-rust  which  has  formed 
into  a  beaker.  Scatter  the  sample  evenly  over  the  bottom  of  the 
dish  to  expose  the  iron  as  much  as  possible  to  the  action  of  the 
moist  air,  and  cover  the  dish  and  beaker  carefully.  Repeat  this 
operation  once  or  twice  a  day  until  the  iron  is  completely  oxi- 
dized. Siphon  off  as  much  of  the  clear  liquid  in  the  beaker  as 
possible,  dissolve  the  oxide  of  iron  in  dilute  HC1,  filter,  and  deter- 
mine the  carbon  by  one  of  the  previously  described  methods. 


THE   CHEMICAL   ANALYSIS   OF  IRON. 

DETERMINATION   OF    GRAPHITIC    CARBON. 

Karsten  gave  the  first  information  in  regard  to  the  existence 
of  graphite  in  pig-iron,  and  he  suggested  dissolving  the  sample 
in  HNO3  with  the  addition  of  a  few  drops  of  HC1,  in  HC1  alone, 
or  in  dilute  H2SO4,  boiling  the  residue  with  caustic  potassa,  filter- 
ing, washing  again  with  HC1,  and  finally  with  water,  and  weighing 
the  residue  as  graphite.  A  very  interesting  comparison  of  the 
results  obtained  by  the  use  of  different  solvents  is  given  by 
Drown,*  and  many  experiments  seem  to  show  that  the  amount  of 
graphite  found  varies  with  the  different  acids  used  to  dissolve  the 
sample,  and  also  with  the  variations  of  treatment  when  the  same 

Solution  acid  is  used.  The  usual  method  is  as  follows :  Treat  I  gramme 
of  pig-iron  or  10  grammes  of  steel  with  an  excess  of  HC1,  i.i 
sp.  gr.  When  all  the  iron  is  dissolved,  boil  for  a  few  minutes, 
allow  the  graphite  to  settle,  and  decant  the  supernatant  fluid  on 
an  asbestos  filter,  using  either  the  perforated  boat,  page  122,  or 
the  glass  filtering-tube,  page  128.  Wash  several  times  with  hot 
water  by  decantation,  then  pour  on  the  residue  in  the  beaker  30 
c.c.  of  a  solution  of  caustic  potassa,  sp.  gr.  i.i,  and,  when  the  effer- 
vescence ceases,  heat  the  solution  to  boiling.  Filter  on  the  same 
filter,  transfer  the  graphite,  etc.,  to  the  filter,  wash  with  hot  water 
again,  and  finally  with  alcohol  and  ether.  Burn  the  graphite  by 
one  of  the  methods  given  under  "  Determination  of  Total  Carbon," 
and  from  the  weight  of  CO2  obtained  calculate  the  percentage 

Comparison    of  carbon  existing  as  graphite.     It  frequently  happens,  when  the 

of  results 

obtained     sample  is  3.  high  steel,  that  the  residue  which  remains  after  treat- 
solving       m£  it  as  above  is  black,  and  contains  carbon,  but  it  is  not  crystal- 
line in  appearance,  and  bears  no   resemblance  to  graphite.     The 
HN03.       same  steel  will  dissolve  completely  in  HNO3,  and  when  filtered 
will   not  leave  a  trace  of  carbon   on  the  felt.     Steels   containing 
graphite  give  appreciably  less   carbon  when   dissolved  in  HNO3 
than   when   dissolved  in  HC1.     It  is,   of  course,  possible  that  a 

*  Trans.  Inst.  Min.  Engineers,  vol.  iii.  p.  42. 


ANALYSIS   OF  IRON  AND   STEEL.  I4 

small  amount  of  very  finely  divided  graphite  may  be  oxidized  by 
the  HNO3,  but,  taking  everything  into  consideration,  it  would  seem 
that  the  method  giving  probably  the  most  accurate  and  certainly 
the  most  uniform  results  is  as  follows :  Dissolve  the  weighed  Solution  in 
sample  in  HNO3,  sp.  gr.  1.2,  using  15  c.c.  of  acid  to  each  gramme 
taken  for  analysis.  Filter  on  the  perforated  boat  or  on  an  ignited 
asbestos  filter,  in  a  glass  tube,  transfer  the  residue  to  the  filter,  and 
wash  thoroughly  with  hot  water.  Treat  the  residue  on  the  filter 
with  hot  caustic  potassa  solution,  i.i  sp.  gr.  (as  the  Si  is  all  oxi- 
dized to  SiO2  there  will  be  no  effervescence),  wash  thoroughly 
with  hot  water,  then  with  a  little  dilute  HC1,  and  finally  with  hot 
water.  Burn  the  carbon  by  one  of  the  methods  previously  men- 
tioned and  calculate  the  CO2  obtained  to  carbon,  and  call  the 
result  graphite. 

DETERMINATION    OP    COMBINED   CARBON. 

Indirect  Method. 

Having  determined  the  total  carbon  and  the  graphite,  by  sub- 
tracting the  latter  from  the  former  we  obtain  the  amount  of  carbon 
existing  in  the  combined  condition. 

Direct  Method. 

This  method  was  first  introduced  by  Eggertz,*  in  1862,  and  is 
now  used  in  every  steel-works  of  any  importance  in  the  world. 
It  is  based  on  the  fact  that  when  steel  containing  carbon  is  dis- 
solved in  HNO3,  1.2  sp.  gr.,  the  carbon,  which  sometimes  at  first 
separates  out  in  flocks  of  a  brownish  color,  is  eventually  dis- 
solved, giving  to  the  solution  a  depth  of  color  directly  propor- 
tionate to  the  amount  of  combined  carbon  in  the  steel.  To  use 
this  in  practice  it  is  only  necessary  to  determine  very  accurately 
the  amount  of  combined  carbon  contained  in  a  steel,  by  a  com- 

*  Jern-Kontorets  Annaler,  1862,  p.  54  ;  1874,  p.  176;  1881,  p.  301 ;  Chem.  News, 
vii.  p.  254;  xliv.  p.  173. 


142 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


Limitation 
in  the  use 
of  this 
method. 


Details 
of  the 
method. 


bustion  method,  and  to  compare  the  depth  of  color  in  a  solution 
of  this  standard  with  that  of  any  unknown  steel,  in  order  to  ascer- 
tain the  amount  of  carbon  in  the  latter.  There  is,  however,  a 
limitation  in  the  application  of  this  method,  which  was  at  first 
entirely  overlooked,  and  even  now  is  not  generally  understood. 
Reference  was  made  on  page  107  to  the  fact  that  combined  carbon 
is  now  believed  to  exist  in  two  conditions  in  steel,  or  rather  that 
under  certain  circumstances  a  portion  of  the  combined  carbon 
changes  its  condition,  and,  from  a  chemical  point  of  view,  while 
it  is  still  combined  carbon,  in  that  it  is  soluble  in  HNO3,  it  fails  to 
impart  so  dark  a  color  to  its  nitric  acid  solution  as  it  did  in  its 
original  state.  The  circumstances  under  which  a  change  of  this 
kind  occurs  are  quite  well  known,  and  are  merely  those  occa- 
sioned by  the  mechanical  treatment  to  which  steel  is  submitted, 
such  as  hammering,  rolling,  hardening,  tempering,  etc.*  It  may 
be  stated,  then,  as  a  general  proposition,  that  the  standard  steel  for 
the  color-test  should  be  of  the  same  kind  and  in  the  same  physical  con- 
dition as  the  samples  to  be  tested. 

To  obtain  the  best  results  samples  should  be  taken  from  the 
original  ingots  that  have  not  been  reheated,  rolled,  or  hammered; 
Bessemer  steel  should  be  compared  with  Bessemer,  crucible  with 
crucible,  open  hearth  with  open  hearth  ;  the  standard  should  con- 
tain approximately  the  same  amount  of  carbon  as  the  samples  to 
be  tested,  and  should  have  as  nearly  as  possible  the  same  chemical 
composition.  The  only  elements  that  seem  to  have  any  decided 
effect  on  the  color  of  the  nitric  acid  solution  are  copper,  cobalt, 
and  chromium. 

Weigh  out  carefully  .2  gramme  of  each  sample,  including  the 
standard,  into  test-tubes  6  inches  (150  mm.)  long  and  ^  inch  (16 

*  Two  veiy  interesting  papers  on  this  subject  will  be  found  in  the  Chem.  News, 
J.  S.  Parker,  "On  the  Varying  Condition  of  Carbon  in  Steel,"  xlii.  p.  88;  T.  W. 
Hogg,  "On  the  Condition  of  Carbon  in  Steel,"  xlii.  p.  130.  In  my  own  practice  I 
have  seen  one-third  of  the  total  carbon  changed  from  the  combined  form  to  the 
graphitic  in  a  high  carbon  steel  by  heating  and  hammering  the  ingot. 


FIG.  70. 


ANALYSIS  OF  IRON  AND  STEEL. 

mm.)  in  diameter.     The  test-tubes  should  be  perfectly  clean  and 

dry,  and  each  one  marked  with  the  number  of  the  sample  on  a 

small  gummed  label  near  the  top.     A  little  wooden  rack  (Fig.  70) 

is  convenient  for  holding 

the      test-tubes      in      the 

weighing-room,     and     to 

avoid  all  chance  of  error 

the  tube  is  not  placed  in 

the  rack  until  the  sample 

has  been  weighed  and  is 

ready   to    be    transferred. 

A  little  platinum  or  aluminium  dish  about  i}4  inches  (40  mm.) 

in    diameter,    with   a   spout,    and   furnished   with    a   counterpoise 

(Fig.  42,  page   30),  is  very  convenient  for  holding  the  drillings, 

which  are  brushed  from  it  into  the  test-tube  with  a  camel's-hair 

brush.     A  very  excellent  form  of  water-bath  is  shown  in  Fig.  71. 


H3 


FIG.  71. 


It  may  be  provided  with  a  constant  level  arrangement,  consisting  Description 

of  water- 


of  a  tubulated  bottle,  the  height  of  the  end  b  of  the  vertical  tube 
a  fixing  the  level  of  the  water  in  the  bath.     A  is  the  bath,  and 


bath. 


144 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


Amount  of 
HN08  to 
be  used. 


Time  re- 
quired 
for  the 
solution. 


B  the  rack.  The  top  of  the  rack  is  of  sheet-copper,  perforated 
to  receive  the  test-tubes,  the  bottoms  of  which  rest  on  the 
coarse  copper  gauze,  which  is  joined  to  the  top  by  the  uprights  C. 
The  top  of  the  rack  rests  on  a  flange  around  the  top  of  the  bath. 

Place  the  test-tubes  in  the  rack  B,  and  stand  the  rack  in  the 
bath  which  contains  cold  water.  Drop  into  each  test-tube  from 
a  pipette  the  proper  amount  of  HNO3,  sp.  gr.  1.2.  For  steels 
containing  less  than  .3  per  cent  carbon  use  3  c.c.  HNO3;  from 
.3  to  .5  per  cent,  carbon,  4  c.c. ;  from  .5  to  .8  per  cent,  5  c.c. ; 
from  .8  to  I  per  cent.,  6  c.c. ;  and  over  i  per  cent.,  7  c.c. 
An  insufficient  amount  of  acid  gives  the  solution  a  slightly 
darker  tint  than  it  should  properly  have. 

The  HNO3  is  made  by  adding  its  own  volume  of  water  to 
acid  of  the  usual  strength,  1.4  sp.  gr.  It  should  be  absolutely 
free  from  chlorine  or  hydrochloric  acid,  as,  according  to  Eggertz, 
.0001  gramme  Cl  in  a  nitric  acid  solution  of  .1  gramme  iron  in 
2.5  c.c.  HNO3  gives  a  decided  yellow  color.  The  HNO3  should 
be  added  slowly,  to  prevent  violent  action,  and  the  drillings  should 
not  be  too  fine,  for  the  same  reason.  Place  in  the  top  of  each 
test-tube  a  small  glass  bulb*  or  a  very  small  funnel,  and  heat  the 
water  in  the  bath  to  boiling,  and  boil  until  all  the  carbonaceous 
matter  is  dissolved,  shaking  the  tubes  from  time  to  time  to  pre- 
vent the  formation  of  any  little  film  of  oxide.  The  time  required 
for  solution  is  for  low  steels  about  twenty  minutes,  and  for  high 
steels  (over  I  per  cent,  carbon)  forty-five  minutes.  After  entire 
solution  of  the  carbonaceous  matter,  prolonged  heating  tends  to 
make  the  color  lighter;  therefore,  as  soon  as  the  absence  of 
small  bubbles  and  the  disappearance  of  any  brownish  flocculent 
matter  show  complete  solution,  remove  the  rack  from  the  bath 
and  stand  it  in  a  dish  of  cold  water.  The  dish  should  be  about 


*  These  bulbs  are  easily  made  by  sealing  one  end  of  a  glass  tube  in  the  blow- 
pipe flame,  heating  it,  blowing  a  bulb  of  the  proper  size,  allowing  it  to  cool,  heating 
it  above  the  neck,  and  drawing  it  out  as  shown  in  Fig.  70. 


ANALYSIS   OF  IRON  AND   STEEL. 


FIG.  72. 


the  same  size  as  the  bath,  so  that  the  top  will  be  covered  by  the 
top  of  the  rack,  thus  excluding  the  light  from  the  solutions,  in 
which  case  the  color  will  not  fade  for  a  long  time.  Under  all 
circumstances  the  solutions  should  be  kept  out  of  the  light,  and 
especially  out  of  direct  sunlight,  as  much  as  possible.  If  there 
should  be  necessarily,  in  the  steels  operated  on  at  one  time,  a 
wide  range  in  carbon,  the  test-tubes  should  be  removed  from  the 
bath  as  fast  as  their  respective  contents  are  dissolved  and  placed 
in  cold  water  in  a  dark  place.  The  appearance  of  the  drillings 
will  often  give  an  idea  of  the  approximate  carbon  contents  of  a 
sample,  but  when  there  is  no  clue  whatever,  it  is  best  to 
begin  by  adding  3  c.c.  HNO3  to  the  weighed  portion  in 
the  test-tube,  and  increase  the  amount  I  c.c.  at  a  time  as 
the  depth  of  color  of  the  solution  or  the  amount  of  floc- 
culent  carbonaceous  matter  indicates  a  higher  carbon  per- 
centage. To  compare  the  colors  of  the  solutions,  pour 
the  standard  into  one  of  the  carbon  tubes  (Fig.  72),  wash 
out  the  test-tube  with  a  little  cold  water,  add  it  to  the 
solution  in  the  carbon  tube,  and  dilute  to  a  convenient 
amount. 

This  dilution  .should  be  sufficient  to  make  the  volume 
of  the  diluted  standard  at  least  twice  as  great  as  the 
volume  of  acid  originally  used  to  dissolve  the  sample,  as 
this  amount  of  water  is  necessary  to  destroy  the  color  due 
to  the  nitrate  of  iron.  It  should  not,  however,  greatly 
exceed  this  amount,  and  should  be  in  some  convenient 
multiple  of  the  carbon  contents  of  the  standard  in  tenths 
of  a  per  cent.  Thus,  if  a  standard  contains  .45  per  cent, 
carbon,  dilute  the  solution  in  the  carbon  tube  to  9  c.c., 
then  each  c.c.  will  equal  .05  per  cent.  The  carbon  tubes 
should  be  about  J^  inch  (12  mm.)  in  diameter,  holding  at 
least  30  c.c.,  and  graduated  to  ^  c.c.  The  tubes  should  have 
exactly  the  same  diameter,  and  the  glass  should  be  perfectly  color- 
less and  have  walls  of  the  same  thickness.  They  should,  of 


Comparing 
the 
colors. 


Compari- 
son-tubes. 


146 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


course,  be  most  accurately  graduated.  The  standard  having  been 
prepared,  pour  the  solution  of  the  sample  to  be  tested  into  another 
carbon  tube,  rinse  the  test-tube  into  it  with  a  little  cold  water,  and 
compare  the  colors.  If  the  solution  of  the  sample  is  darker 
than  that  of  the  standard,  add  water,  little  by  little,  shaking  the 
tube  well  to  mix  the  solution  until  the  shades  are  exactly  the 
same.  Allow  a  minute  or  two  for  the  solution  to  run  down  the 
walls  of  the  tube,  and  read  the  volume.  If  the  standard  was 
diluted  as  above,  then,  of  course,  each  c.c.  will  equal  .05  per  cent, 
carbon,  and  if  the  volume  of  the  sample  is  10.5  c.c.  it  will  contain 
.525  per  cent,  carbon.  If  the  solution  of  the  sample  when  first 
transferred  to  the  tube  should  be  lighter  in  color  than  the  standard, 
a  lower  standard  must  be  used,  or  this  one  may  be  diluted  to,  say, 
13.5  c.c.,  in  which  case  the  number  of  c.c.  divided  by  3  will  give 
the  percentage  of  carbon  in  tenths.  The  color  may  be  compared 
by  holding  the  two  tubes  in  front  of  a  piece  of  white  paper  held 
towards  the  light,  but  a  camera  made  of  light  wood  and  blackened 
inside  is  most  convenient,  and  at  night  is  quite  invaluable.  It  is 
Description  showrn  in  Fig.  73,  and  consists  of  a  box  3^  inches  (90  mm.)  high 

of  camera.  .  ,  /    •       i  /    r.  \        •  i 

FIG.  73.  inside,  iy2  inches  (38  mm.)  wide 

at  one  end,  and  5  inches  (127 
mm.)  at  the  other.  It  is  24 
inches  (610  mm.)  long,  and  is 
supported  on  a  rod,  which  can  be 
raised  and  lowered  to  suit  the 
convenience  of  the  observer. 
The  small  end  is  closed  by  a 
piece  of  ground-glass,  which 
slides  in  through  a  slot  on  top 
i  inch  (25  mm.)  from  the  end. 
Immediately  beyond  this  is  an- 
other slot  to  receive  a  thin  piece 

of  faintly  blue  glass,  which  is  inserted  when  the  tests  are  made  at 
night,  using  an  oil-lamp  placed  on  a  stand  just  beyond  the  camera. 


ANALYSIS   OF  IRON  AND  STEEL. 

Two  holes  in  the  top  of  the  camera  just  inside  the  ground-glass 
screen  receive  the  carbon  tubes,  the  ends  of  which  rest  on  a  piece 
of  black  cloth  on  the  bottom  of  the  camera  inside.  Another  piece 
of  black  cloth  fastened  across  the  top  of  the  camera,  covering  the 
top  of  the  ground-glass  slide,  and  having  holes  just  large  enough  to 
admit  the  tubes,  excludes  all  light  except  that  at  the  back  of  the 
tubes.  A  north  light  is  much  the  best  for  comparing  the  colors,  and, 
as  to  most  observers  the  left-hand  tube  appears  a  little  the  darker, 
the  color  will  be  exactly  matched  when,  the  tubes  being  reversed, 
the  left-hand  tube  still  appears  a  little  the  darker  of  the  two. 

Instead  of  diluting  the  solutions  to  agree  with  a  standard,  as 
above  described,  some  chemists  use  a  rack  of  permanent  stand- 
ards, as  suggested  by  Britton.*  The  principal  difficulty  hereto- 
fore  attending  the  use  of  permanent  standards  has  been  the  im-  standards. 
possibility  of  preventing  their  fading  ;  but,  according  to  Eggertz,f 
this  is  now  entirely  overcome  by  the  method  of  preparing  them 
suggested  by  Prof.  F.  L.  Ekman.  The  details  are  as  follows  :  Dis- 
solve 3  grammes  of  neutral  ferric  chloride  in  100  c.c.  water  con- 
taining 1.5  c.c.  HC1;  dissolve  2.1  grammes  cupric  chloride  in  100 
c.c.  water  containing  .5  c.c.  HC1;  dissolve  2.1  grammes  cobaltic 
chloride  in  100  c.c.  water  containing  5  c.c.  HC1,  using  the  neutral 
salts  in  all  cases.  These  solutions  will  contain  about  .01  gramme  Preparation 

of  the 

of  the  metal  to  the  c.c.,  and  by  adding  to  8  c.c.  of  the  iron  solu-     solution. 

tion  6  c.c.  of  the  cobalt  solution,  3  c.c.  of  the  copper  solution, 

and  5  c.c.  water  containing  .5  per  cent.  HC1,  a  liquid  is  obtained 

which  has  a  color  approximating  to  that  obtained  by  dissolving 

.2  gramme  of  steel,  containing  I  per  cent,  of  carbon,  in  HNO3  and 

diluting  to  10  c.c.,  or  .1  per  cent,  carbon  to  the  c.c.     Prepare  a 

number  of  test-tubes  of  the  size  described  on  page  142,  but  in  this 

case  it  is  essential  that  they  should  be  of  exactly  the  same  diam- 

eter, and  that  the  glass  should  be  as  nearly  colorless  as  possible,  preparation 

By  successive  dilutions  with  water  containing  .5  per  cent.  HC1, 


Chem.  News,  xxii.  101.  f  Chem.  News,  xliv.  173. 


1 48  THE   CHEMICAL  ANALYSIS   OF  IRON. 

of  the  normal  solution  prepared  as  above,  make  solutions  of  about 
the  proper  strength  for  the  series  required. 

The  variations  should  be  about  .02  per  cent,  between  the  differ- 
ent tubes  of  the  series,  corresponding  to,  say,  the  even  hundredths. 
There  should  be  about  10  c.c.  of  solution  in  each  tube,  and  then 
the  color  of  each  should  be  compared  with  a  standard  steel, 
diluted  to  the  exact  strength  required  in  the  permanent  standard. 
For  example,  if  the  standard  steel  contains  .4  per  cent,  carbon,  and 
you  wish  to  get  the  exact  color  for  the  .32  per  cent,  carbon  tube 
in  the  permanent  series,  then  dissolve  .2  gramme  of  the  standard 
exactly  as  directed  on  page  144,  pour  the  solution  into  a  carbon 
tube,  and  dilute  it  in  accordance  with  the  formula,  carbon  required 
:  carbon  of  standard  : :  10  c.c.  :  the  number  of  c.c.  required,  or,  in 
this  case,  32  :  40  : :  10  c.c.  :  12.5  c.c.  Therefore  dilute  the  solu- 
tion in  the  carbon  tube  to  12.5  c.c.,  pour  10  c.c.  into  a  test-tube 
exactly  like  those  used  for  the  permanent  standards,  and  compare 
it  with  the  .32  per  cent,  carbon  tube.  If  the  color  of  the  perma- 
nent solution  is  not  exactly  the  same,  correct  it  by  adding  por- 
tions of  the  solutions  of  the  iron,  cobalt,  or  copper  salts,  or  water 
containing  .5  per  cent.  HC1.  The  iron  salt  or  HC1  alone  gives  a 
yellowish,  the  cobalt  salt  a  brownish,  and  the  copper  salt  a  green- 
ish, tone  to  the  solution.  The  standards  may  now  be  arranged  in 
a  rack,  as  shown  in  Fig.  74.  The  colors  of  the  permanent  stand- 

FIG.  74. 


OJUJJULi 


ards  once  fixed,  the  samples  to  be  analyzed  are  treated  exactly  as 

described  on  page    144,  the  test-tubes  used  being  precisely  like 

method       those  containing  the  permanent  standards,  and  each  one  carefully 

Ts'ingper-    graduated  to  contain  10  c.c.     When  the  samples  (.2  gramme  each) 

manent      are  dissolved  and  cooled,  dilute  each  solution  in  turn  with  cold 

standards. 

water  to   10  c.c.,  mix  thoroughly,  and  compare  it  with  the  stand- 


ANALYSIS   OF  IRON  AND   STEEL.  . 

ards  in  the  rack,  by  which  means  the  carbon  may  be  estimated 
to  the  nearest  hundredth  of  a  per  cent. 

In  testing  white  cast  iron,  use  only  .05  gramme,  dissolve  in  7  c.c.  White  cast 

iron. 

HNO3,  dilute  the  standard  to  some  convenient  amount  approxi- 
mating .20  c.c.,  and  compare  as  quickly  as  possible  to  avoid  the 
precipitation  of  carbonaceous  matter,  which  is  apt  to  occur  under 
these  circumstances.     The  graphite  in  ordinary  gray  pig-iron,  and 
sometimes  even  in  steels,  renders  filtration  necessary.     In  this  case  Filtering 
add  to  the  cold  acid  solution  one-half  of  its  volume  of  water,  filter     ^hite, 
through  a  small,  dry,  ashless  filter  into  the  carbon  tube,  wash  with 
as  little  water  as  possible,  and  compare  as  usual. 

For  steels  very  low  in  carbon,  the  color  test,  as  above  described, 
becomes  uncertain,  but  Stead*  has  suggested  and  elaborated  a  stead's 
method  which  gives  excellent  results.  It  is  based  on  the  fact  that 
the  carbonaceous  matter  liberated  from  iron  and  steel  is  soluble  in 
the  caustic  alkalies  as  well  as  in  HNO3,  while  the  color  which  it 
imparts  to  the  alkaline  solution  is  about  2^/2  times  as  great  as  that 
which  it  gives  to  the  acid  solution.  For  this  method  is  required, 
besides  the  HNO3,  1.2  sp.  gr.,  a  solution  of  caustic  soda  1.27  sp.  gr. 
Weigh  i  gramme  of  each  sample,  including  the  standard,  into  a 
No.  i  beaker,  add  12  c.c.  HNO3,  and  heat  on  the  bath  until  solution 
is  complete,  which,  in  the  case  of  puddled  iron  or  low  steel,  is  in 
about  five  or  ten  minutes.  Add  to  each  30  c.c.  of  boiling  water 
and  1 3  c.c.  of  the  soda  solution,  stirring  well.  Pour  each  solution 
in  turn  into  a  glass  measuring-jar,  dilute  to  60  c.c.,  mix  thor- 
oughly, allow  the  solution  to  settle,  filter  through  a  dry  filter,  and 
receive  15  c.c.  of  each  sample  in  a  carbon  tube.  Those  samples 
whose  solutions  are  darker  than  that  of  the  standard  contain,  of 
course,  more  carbon  than  the  standard.  Dilute  the  solutions  in 
turn  until  the  colors  agree  with  that  of  the  standard.  The  per- 

ci 
centage  of  carbon  is  deduced   from  the  equation  —  X  b=x,   in 

which  a  is  the  percentage  of  carbon  in  the  standard,  15,  of  course, 

*  Jour.  Iron  and  Steel  Institute,  1883,  No.  i,  p.  213. 


ISO 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


Stead's 
chromom- 
eter. 


FIG.  75. 


the  number  of  c.c.  taken  of  each  solution,  b  is  the  number  of  c.c. 
in  the  diluted  sample,  and  x  is  the  percentage  of  carbon  in  the 
sample.  Take  those  samples  whose  solutions  are  lighter  than 
that  of  the  standard,  and  dilute  the  standard  until  its  color  is  the 
same  as  that  of  the  darkest  of  the  samples,  read  the  volume,  and 
dilute  it  for  the  next  darkest,  and  so  on  through  the  series.  The 
percentage  of  carbon  in  each  sample  is  then  deduced  from  the  equa- 

ci 
tion  y-X  15— '*",  the  letters  having  the  meaning  given  above.    They 

may  also  be  compared  by  pouring  into  measuring-tubes  until  the 
colors  appear  equal  when  looked  at  from  above.  The  carbon 

in  this  case  is  inversely  as  the 
length  of  the  column.  To  facili- 
tate the  comparisons,  Stead  (loc. 
cit^)  has  devised  a  very  simple 
instrument  based  on  this  last 
principle.  It  consists  (Fig.  75) 
of  two  parallel  tubes  of  any  con- 
venient diameter  fastened  to  a 
frame.  The  tube  b  is  open  at 
both  ends,  but  is  contracted  at 
the  point  c.  The  contracted  end 
passes  through  the  stopper  of 
the  bottle  dy  and  reaches  almost 
to  the  bottom  of  the  bottle.  A 
small  tube,  e,  which  ends  just 
below  the  stopper,  is  connected 
with  a  bulb  syringe,  f.  The 
tube  a  is  closed  at  the  lower 
end,  and  contains  a  small,  solid, 
glazed  china  cylinder,  which 
rests  on  the  bottom.  A  similar 
cylinder  rests  just  above  the 
contraction  in  the  tube  b,  and  the  tubes  are  so  arranged  that  the 


ANALYSIS   OF  IRON  AND   STEEL. 

upper  flat  surfaces  of  the  cylinders  are  on  the  same  level,  and 
exactly  the  same  distance  from  the  open  tops  of  the  tubes.  The 
scale  g  is  graduated  in  .02  up  to  .20  from  the  level  of  the  upper 
surfaces  of  the  cylinders  to  a  point  marked  on  the  tube  a,  10 
inches  (254  mm.)  above.  A  solution  of  a  standard  steel  contain- 
ing .2  per  cent,  carbon,  prepared  as  above,  is  placed  in  the  bottle 
d,  and  a  similar  solution  of  a  sample  to  be  tested  is  poured  into 
the  tube  a  up  to  the  mark.  By  squeezing  the  bulb  /  a  column 
of  the  standard  solution  is  forced  up  the  tube  b,  and  when,  by 
looking  into  the  mirror,  placed  at  an  angle  of  45°,  the  color  in  the 
two  columns  appears  equal  in  intensity,  the  percentage  of  carbon 
is  read  off  on  the  scale  opposite  the  top  of  the  column  in  b.  The 
alkaline  solution  is  said  to  keep  its  color  unaltered  for  a  month 
when  not  exposed  to  direct  sunlight. 


DETERMINATION    OF  TITANIUM. 
By  Precipitation. 

Only  traces  or  very  minute  amounts  of  titanium  are  found  in 
steel,  but  notable  quantities  exist  in  some  kinds  of  pig-iron. 
As  pointed  out  by  Riley,*  when  pig-iron  containing  titanium  is 
dissolved  in  HC1  a  portion  of  the  titanium  goes  into  solution, 
while  the  remainder  is  found  with  the  insoluble  matter.  The 
insoluble  portion,  as  noticed  on  page  77  et  seq.,  contains  P2O5. 
It  is  a  curious  fact  that  while  TiO2  interferes  with  the  deter-  insoluble 
mination  of  P2O5  by  its  tendency  to  form  upon  evaporation  to 
dryness  an  insoluble  phospho-titanate,  so  P2O5  interferes  with  the 
determination  of  TiO2  by  partially  preventing  the  precipitation  of 
TiO2  from  its  boiling  sulphuric  acid  solution.  The  best  method, 
therefore,  for  the  determination  of  titanium  is  to  proceed  exactly 

*  Jour.  Chem.  Soc.,  xvi.  387. 


152 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Separation 
from  P2O5 
by  fusion 
with 

Na2CO3. 


Fusion 
with 
KHS04. 


Solution  of 
the  bisul- 
phate  in 
water. 


as  for  the  determination  of  phosphorus  when  titanium  is  present, 
as  directed  on  page  77  et  seq.,  until  the  residue  from  the  aqueous 
solution  of  the  carbonate  of  sodium  fusion  is  obtained.  Dry  this 
residue,  transfer  it  to  a  large  platinum  crucible,  preferably  the 
one  in  which  the  carbonate  of  sodium  fusion  was  made,  burn 
the  filter,  add  its  ash  to  the  residue,  and  fuse  the  whole  with 
15  or  20  times  its  weight  of  bisulphate  of  potassium.  In  fusing 
with  bisulphate  of  potassium  it  is  necessary  to  begin  with  a  very 
low  heat,  and  to  raise  the  temperature  very  slowly  and  carefully 
to  a  low  red  heat,  as  the  mixture  has  a  strong  tendency  to  boil 
over  the  top  of  the  crucible  whenever  the  temperature  is  increased 
too  rapidly.  When  the  lid  of  the  crucible  is  raised,  fumes  of  SO3 
should  come  off,  and  the  fusion  should  be  kept  at  this  point  for 
several  hours,  or  until  it  is  quite  clear  and  the  whole  of  the 
ferric  oxide  has  been  dissolved.  Incline  the  crucible  as  far  as 
possible  on  one  side  while  the  fused  mass  is  still  liquid,  and  allow 
it  to  cool  in  this  position.  The  mass  will  harden  in  a  cake  on 
the  side  of  the  crucible,  and  can  be  readily  detached  without 
bending  the  sides  of  the  crucible.  Place  the  crucible  and  lid 
in  a  No.  4  beaker,  and  suspend  in  the  beaker  a  little  platinum 
wire-gauze  basket  containing  the  fused  mass,  as  shown  in  Fig. 
69,  page  138.  Pour  into  the  beaker  50  c.c.  of  strong  sulphurous 
acid  water,  and  fill  the  beaker  to  the  top  of  the  fused  mass  in 
the  basket  with  cold  water.  Under  these  circumstances  the  fused 
mass  dissolves  quite  rapidly,  as  the  concentrated  solution  falls  to 
the  bottom,  and  the  iron  is  at  the  same  time  deoxidized.  Without 
the  basket,  it  is  necessary  to  stir  the  liquid  constantly,  and  the 
time  occupied  in  dissolving  the  fused  mass  is  much  prolonged. 
When  solution  is  complete,  remove  the  basket,  the  crucible,  and 
the  lid  from  the  beaker,  wash  them  with  a  jet  of  cold  water,  and 
filter  the  solution  into  a  No.  5  beaker.  Add  a  filtered  solution 
of  20  grammes  acetate  of  sodium  and  one-sixth  the  volume  of 
the  solution  of  acetic  acid,  1.04  sp.  gr.,  to  the  filtered  solution, 
and  heat  to  boiling.  The  titanic  acid  is  precipitated  almost  imme- 


ANALYSIS   OF  IRON  AND   STEEL.  jco 

diately  in  a  flocculent  condition,  and  quite  free  from  iron.  Boil 
for  a  few  minutes,  allow  the  titanic  acid  to  settle,  filter,  wash 
with  hot  water  containing  a  little  acetic  acid,  dry,  ignite,  and 
weigh  as  TiO2,  which  contains  60.98  per  cent.  Ti.  Instead  of 
fusing  the  residue  from  the  aqueous  solution  of  the  carbonate 
of  sodium  fusion  with  bisulphate  of  potassium,  the  operation  may 
be  hastened  as  follows : 

Transfer  the  residue  to  the  large  crucible,  as  before  directed,  Treatment 
and   fuse  with    5    grammes  of  dry  carbonate  of  sodium.     Allow     Lion  with* 
the  crucible  to  cool,  and  then  pour  into  it  very  gradually  strong     HaSO* 
H2SO4.     When    the    effervescence    slackens,   warm   the    crucible 
slightly   and   continue    the    addition    of    H2SO4   and   the   careful 
application  of  heat  until  the  fusion  becomes  liquid  and  the  ferric 
oxide   is   all    dissolved.      Heat   carefully  until    copious   fumes    of 
SO3  are  given  off,  allow  the  crucible  to  cool,  and  pour  the  con- 
tents, which  should  be  just  fluid  when  cold,  into  a  beaker  con- 
taining  about    250  c.c.  of  cold  water.     Add  to  it    50  c.c.  of  a 
strong   aqueous  solution  of  sulphurous   acid,  or    2    or    3    c.c.  of 
bisulphite  of  ammonium,  filter  if  necessary,  nearly  neutralize  by 
NH4HO,  allow  it   to  stand    until  it  is   entirely  decolorized,  add 
20  grammes  acetate  of  sodium  and  one-sixth  its  volume  of  acetic 
acid,   1.04  sp.  gr.,  and  precipitate  the  TiO2  as  before. 

By  Volatilization. 

Drown*  suggested  the  method  of  determining  titanium  by 
volatilizing  it  in  a  current  of  chlorine  gas.  The  details,  with 
some  modifications,  are  as  follows.  Treat  the  sample  exactly  as 
directed  for  the  determination  of  silicon,  by  volatilization  in  a 
current  of  chlorine  gas,  page  65  et  seq. 

To  the  filtrate  from  the  silica,  page  68,  add  a  slight  excess 
of  NH4HO,  acidulate  with  acetic  acid,  boil,  filter,  wash,  and 
ignite  the  precipitate.  As  this  precipitate  may  contain  a  little 

*  Trans.  Inst.  Min.  Engineers,  viii.  508. 
ii 


154 


THE    CHEMICAL   ANALYSIS   OF  IRON. 

ferric  oxide  (carried  over  mechanically  as  Fe2Cl6),  phosphoric 
acid,  tungstic  acid,  etc.,  fuse  it  with  a  little  carbonate  of  sodium, 
dissolve  the  fused  mass  in  hot  water,  filter,  wash,  dry,  and  ignite 
the  residue,  which  will  contain  all  the  titanic  acid  as  titanate 
of  sodium,  and  any  iron  that  may  have  been  present  as  Fe2O3. 
The  filtrate  will  contain  the  P2O5,  etc.  Fuse  the  ignited  residue 
with  a  little  carbonate  of  sodium,  treat  it  in  the  crucible  with 
strong  H2SO4,  as  directed  on  page  153,  and  determine  the  TiO2 
in  the  manner  there  described. 


DETERMINATION    OF    COPPER. 

For  the  determination  of  copper  the  precipitate  by  H2S,  ob- 
tained in  the  determination  of  phosphorus,  page  74,  may  be  used, 
but  in  this  case  the  precipitate  must  be  filtered  off  before  getting 
rid  of  the  excess  of  H2S,  after  which,  if  any  additional  precipitate 
of  As2S3  is  thrown  down  in  the  filtrate,  it  must  be  filtered  off  before 
proceeding  with  the  determination  of  phosphorus.  Dry  and  ignite 
the  filter  with  the  precipitate  of  CuS,  etc.,  in  a  porcelain  crucible, 
burn  off  all  the  carbon  from  the  paper,  allow  the  crucible  to  cool, 
and  digest  the  precipitate  at  a  gentle  heat  with  HNO3  and  a  few 
drops  of  H2SO4,  keeping  the  crucible  covered  with  a  small  watch- 
glass.  When  the  CuS  is  entirely  dissolved,  remove  the  watch- 
glass  and  evaporate  the  solution  until  all  the  HNO3  is  expelled 
and  fumes  of  SO3  are  given  off.  Allow  it  to  cool,  add  enough 
water  to  dissolve  all  the  CuSO4,  heating  gently,  if  necessary,  and 
etermina-  wash  the  solution  into  a  platinum  crucible.  Place  the  crucible  in 
the  little  brass  holder  (Fig.  76),  and  attach  the  weighed  platinum 


cylinder  and  connect  the  battery.  The  battery  should  consist  of 
three  Daniell's  2-quart  cells,  arranged  as  shown  in  Fig.  77.  The 
connectors  a,  b  pass  through  the  sides  of  the  box  (which  should 
be  kept  covered),  and,  the  jars  being  connected  as  shown  in  the 
sketch,  by  simply  changing  the  wire  from  a  to  by  three  cells  are 


ANALYSIS  OF  IRON  AND  STEEL. 


'55 


FIG.  76. 


Zn 


brought  into  action  instead  of  two.      For   depositing  the  small 
amount  of  copper  found  in  iron  or  steel,  two  cells  furnish  a  suffi- 
ciently strong  current.    The  platinum  cylinder  should  weigh  about 
3   or  4  grammes;    it  is  lowered   into  the 
liquid   until  it  is  just  clear  of  the  bottom 
of  the  crucible,  and  the  crucible  is  covered 
with  two  small  pieces  of  glass  to  prevent 
liquid  being  carried  off  by  the  escaping  gas. 
It   is  much  neater   to  deposit  the   copper 
on  the  cylinder  than  in  the  crucible,  as  it 
weighs  less,  is  quite  as  easy  to  wash  and 
dry,  and  there  is  no  danger  of  any  silica 
or   dirt   from   the  solution   being   covered 
by  the  deposited  copper.     When  the  cop- 
per is  all  deposited,  usually  in  two  or  three 
hours,  remove   the   cylinder,  wash  it  with 
cold  water,  then  with  alcohol,  dry  at  100°  C,  cool,  and  weigh. 
The  increase  of  weight  is  Cu. 

In  pig-irons  containing  titanium  it  is  necessary  to  use  a  separate  Using  soiu- 
portion  for  the  determination  of  copper.  In  steels,  the  solution  in  s°det°rm 
the  flask  from  the  determination  of  sulphur 
(page  53)  may  be  used  for  the  determi- 
nation of  copper.  In  this  case,  wash  the 
contents  of  the  flask  into  a  No.  5  beaker, 
nearly  neutralize  with  NH4HO,  add  5  c.c. 
HC1,  heat  the  solution  to  boiling,  and  pass 
H2S  through  the  boiling  solution  for  fifteen 
or  twenty  minutes,  filter,  wash  with  hot 
water,  and  treat  the  precipitate  as  directed 

above.     In  the  case  of  pig-irons,  however,  it  is  best  to  dissolve  in  Procedure 
aqua  regia,  evaporate  to  dryness,  redissolve  in  HC1,  filter,  reduce     iron. 
the  iron  in  the  filtrate  with  NH4HSO3,  boil  off  the  excess  of  SO2, 
and  precipitate  by  H2S.     Instead  of  using  H2S,  the  copper  may 
be  precipitated  in  a  sulphuric  acid  solution  by  hyposulphite  of 


FIG.  77. 


mination 
in  steels. 


I56 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


Precipita- 
tion by 
hyposul- 
phite of 
sodium. 


Determina- 
tion as 
Cu2S. 


Determina- 
tion as 
CuO. 


sodium.  Dissolve  5  grammes  of  the  sample  in  a  mixture  of  150 
c.c.  H2O  and  12  c.c.  strong  H2SO4.  Dilute  to  about  500  c.c. 
with  hot  water,  heat  to  boiling,  and  add  3  grammes  of  hyposul- 
phite of  sodium  dissolved  in  10  c.c.  hot  water.  Boil  for  a  few 
minutes,  allow  the  precipitate  to  settle,  and  filter  and  wash  with 
hot  water.  Dry  the  precipitate,  which  besides  the  CuS  will  con- 
sist of  the  graphite,  silica,  etc. ;  transfer  it  to  a  small  beaker,  burn 
the  filter,  and  add  the  ash  to  the  main  portion.  Digest  the  whole 
with  aqua  regia,  dilute  with  hot  water,  filter,  wash,  add  a  few 
drops  of  H2SO4,  and  evaporate  until  fumes  of  SO3  are  given  off, 
cool,  dissolve  in  water,  transfer  to  the  platinum  crucible,  and 
determine  the  copper  by  the  battery  as  directed  above. 

Instead  of  determining  the  copper  by  electrolysis,  it  may  be 
determined  as  subsulphide,  Cu2S,  or  as  oxide,  CuO.  To  deter- 
mine it  as  Cu2S,  dilute  the  sulphate  obtained  by  any  of  the 
methods  mentioned  above  with  water  to  about  50  c.c.,  add  an 
excess  of  NH4HO,  filter  from  Fe2O3,  etc.,  wash  with  ammoniacal 
water,  and  pass  H2S  through  the  cold  solution.  Filter,  wash  with 
H2S  water,  dry  the  filter  and  precipitate,  transfer  the  latter  to  a 
small  porcelain  crucible,  burn  the  filter,  and  add  its  ash  to  the 
precipitate.  Add  to  the  precipitate  in  the  crucible  about  twice 
its  volume  of  flowers  of  sulphur  and  ignite  it  in  a  current  of 
hydrogen,  as  directed  for  the  determination  of  manganese  as  MnS, 
page  94.  Weigh  as  Cu2S,  which  contains  79.85  per  cent.  Cu. 

Instead  of  igniting  the  precipitate  obtained  above  as  Cu2S,  the 
copper  may  be  determined  as  CuO,  as  follows :  Dissolve  the  sul- 
phide in  aqua  regia  in  a  small  porcelain  dish,  evaporate  nearly 
dry,  dilute  with  hot  water,  heat  to  boiling,  and  add  a  slight  excess 
of  a  dilute  solution  of  caustic  soda  or  potassa.  Filter  on  a  small 
ashless  filter,  wash  with  hot  water,  dry,  transfer  the  precipitate 
to  a  platinum  crucible,  burn  the  filter  and  add  its  ash  to  the  pre- 
cipitate, moisten  the  whole  with  HNO3,  and  heat  very  gently  at 
first,  but  increase  the  heat  slowly  to  redness.  Cool,  and  weigh  as 
CuO,  which  contains  79.85  per  cent.  Cu. 


ANALYSIS   OF  IRON  AND   STEEL.  l^ 

DETERMINATION  OF  NICKEL  AND  COBALT. 

Treat  3  grammes  of  the  drillings  exactly  as  directed  for  the 
determination  of  manganese  by  the  acetate  method,  page  90  et  seq. 
The  precipitate  by  H2S,  page  92,  will  contain  all  the  nickel  and 
cobalt  and  a  portion  of  the  copper  contained  in  the  sample.  Filter 
this  precipitate  on  a  small  washed  filter,  wash  with  H2S  water  con- 
taining a  little  free  acetic  acid,  dry  and  ignite  the  filter  and  pre- 
cipitate, and  transfer  them  to  a  No.  I  beaker.  Dissolve  in  HC1 
with  a  few  drops  of  HNO3,  evaporate  to  dryness,  redissolve  in 
10-20  drops  of  HC1,  dilute  with  hot  water  to  about  50  c.c.,  heat  the 
solution  to  boiling,  and  pass  a  stream  of  H2S  through  the  boiling  Separation 

from  Cu. 

solution  to  precipitate  any  copper  that  may  be  present.  Filter, 
wash  with  hot  water,  evaporate  the  filtrate  to  dryness,  moisten  the 
dry  mass  with  4  or  5  drops  of  HC1,  add  20  or  30  drops  of  cold 
water,  and  then  2  or  3  grammes  of  nitrite  of  potassium  (KNO2)* 
dissolved  in  the  least  possible  amount  of  water,  and  acidulated 
with  acetic  acid.  The  presence  of  cobalt  is  shown  by  the  forma-  Separation 

of  Ni  and 

tion  of  a  bright  yellow  precipitate  of  the  double  nitrite  of  cobalt  Co. 
and  potassium,  (KNO2)6Co2(NO2)6  +  Aq.  Stir  the  solution,  and 
allow  it  to  stand  twenty-four  hours,  with  occasional  stirring.  Fil- 
ter on  a  small  ashless  filter,  wash  with  water  containing  acetate  of 
potassium  and  a  little  free  acetic  acid,  remove  the  filtrate  which 
contains  the  nickel,  and  wash  the  precipitate  and  filter  free  from 
acetate  of  potassium  with  alcohol.  Ignite  the  filter  and  precipitate 
carefully  in  a  porcelain  crucible,  being  careful  not  to  raise  the  Determina- 

tion  of  Co. 

temperature  high  enough  to  fuse  the  precipitate;  transfer  to  a 
very  small  beaker,  and  digest  in  HC1  and  a  little  KC1O3.  Evapo- 
rate to  dryness,  redissolve  in  3-5  drops  of  HC1,  dilute  with  cold 
water,  add  about  I  gramme  of  acetate  of  sodium,  and  boil  for  an 
hour  to  precipitate  the  small  amount  of  Fe2O3  and  A12O3  that  is 
always  present.  Filter,  to  the  filtrate  add  excess  of  NH4HO  and 
NH4HS,  and  heat  to  boiling.  As  soon  as  the  precipitate  of  CoS 

*  See  page  41. 


I58 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


has  settled,  filter,  wash  with  water  containing  a  little  NH4HS,  dry 
and  ignite  the  precipitate  and  filter,  in  a  platinum  crucible.  When 
all  the  carbon  is  burned,  allow  the  crucible  to  cool,  pour  in  a  little 

AsCoSO4.  HNO3,  heat  carefully,  and  finally  evaporate  to  dryness.  Add  a 
few  drops  of  H2SO4,  digest  until  the  sulphide  and  oxide  are 
changed  to  sulphate  of  cobalt,  drive  off  the  excess  of  H2SO4,  heat 
finally  to  dull  redness  for  a  few  moments,  cool,  and  weigh  as 
CoSO4,  which  contains  37.98  per  cent,  of  cobalt.  Heat  the  filtrate 
from  the  double  nitrite  of  cobalt  and  potassium  to  boiling,  add  a 
slight  excess  of  caustic  potassa,  boil  for  a  few  minutes,  filter,  and 

Determina-  wash  the  precipitate  of  oxide  of  nickel  with  hot  water.  Dis- 
solve the  precipitate  on  the  filter  with  HC1,  allow  the  solution  to 
run  back  into  the  beaker  in  which  the  oxide  of  nickel  was  pre- 
cipitated, and  wash  the  filter  with  hot  water.  Evaporate  the 
solution  to  dryness,  redissolve  in  3-5  drops  of  HC1,  dilute  with 
cold  water  to  about  50  c.c.,  add  about  I  gramme  of  acetate  of 
sodium,  boil  for  about  an  hour,  filter  off  any  Fe2O3  and  A12O3,  and 
wash  with  hot  water.  To  the  filtrate  add  an  excess  of  NH4HS 
(a  brown  color  shows  the  presence  of  nickel),  acidulate  with  acetic 
acid,  heat  to  boiling,  and  pass  a  current  of  H2S  through  the  boil- 
ing solution  until  the  precipitated  sulphur  and  sulphide  of  nickel 
agglomerate.  Filter,  wash  with  H2S  water,  dry  and  ignite  the 

AS  Ni2s  or     filter,  and  precipitate.     Allow  the  crucible  to  cool,  add  a  little  car- 

NiO. 

bonate  of  ammonium  to  the  precipitate,  heat  to  dull  redness,  and 
volatilize  any  sulphuric  acid  that  may  have  been  formed  as  sul- 
phate of  ammonium,   cool,   and  weigh   as    Ni2S    or    NiO,  which 
contains  78.59  per  cent,  of  nickel.     The  nickel  and  cobalt  may 
also  be  weighed  in  the  metallic  condition  by  precipitating  them  by 
Determina-     the  battery  from  the  ammoniacal  solutions  of  the  sulphates.     If  it 
eiectroiy-     is  not  desired  to   separate  them,  evaporate  the  filtrate  from  the 
S+Co.  l     precipitated  sulphide  of  copper  with  an  excess  of  H2SO4  until  the 
HC1  is  driven  off  and  fumes  of  SO3  appear,  allow  the  beaker  to 
cool,  add  about   5   c.c.  water,  then  an  excess  of  NH4HO,  filter 
if  necessary,  transfer  to  a  platinum  crucible,  and  precipitate  on  the 


ANAL  YSIS   OF  IRON  AND   STEEL. 

small  cylinder  (Fig.  76,  page  155)  in  a  strongly  ammoniacal  solu- 
tion, using  three  cells  of  the  battery.  Wash  the  cylinder  with 
water,  then  with  alcohol,  dry  at  100°  C,  and  weigh  as  Ni  -f  Co. 
To  determine  the  nickel  and  cobalt  separately,  precipitate  the  cobalt 
as  double  nitrite  of  cobalt  and  potassium,  treat  the  ignited  cobalt 
precipitate  with  an  excess  of  H2SO4,  heat  until  fumes  of  SO3  are 
given  off,  dilute  a  little,  make  the  solution  strongly  ammoniacal, 
and  precipitate  the  cobalt  as  above  directed.  Precipitate  the  NiO, 
in  the  filtrate  from  the  cobalt,  by  KHO  solution,  filter,  wash,  dis- 
solve on  the  filter  in  HC1,  evaporate  the  solution  with  H2SO4,  add  Determina- 
excess  of  NH4HO,  and  precipitate  the  Ni  by  the  battery  as 
above. 


DETERMINATION    OF    CHROMIUM   AND   ALU- 
MINIUM. 

Weigh  5  grammes  of  drillings  into  a  flask  of  about  500  c.c. 
capacity,  and  pour  in  20  c.c.  strong  HC1  diluted  with  3  or  4  times 
its  bulk  of  water.  Close  the  flask  with  a  rubber  stopper  carrying 
a  valve  which  is  made  as  follows.  Bore  a  hole  through  the  centre  Bunsen 
of  a  rubber  stopper,  and  insert  a  piece  of  glass  tubing  long  enough 
to  extend  from  the  small  end  of  the  stopper  to  a  distance  of  I  inch 
(25  mm.)  beyond  the  large  end.  Take  a  piece  of  heavy  soft  rubber 
tubing  2  inches  (50  mm.)  long,  and  cut  a  longitudinal  slit  in  the 
middle  about  y2  inch  (12  mm.)  long.  Close  one  end  of  the  tube 
with  a  piece  of  glass  rod  y2  inch  (12  mm.)  long,  and  fit  the  other 
end  over  the  glass  tube  in  the  stopper  for  a  distance  of  y2  inch 
(12  mm.).  This  valve  allows  the  gas  to  escape  from  the  flask,  but 
prevents  air  from  entering  it,  so  that  the  iron  is  not  oxidized,  but 
remains  dissolved  as  ferrous  chloride.  Heat  the  dilute  acid  in  the 
flask  if  necessary,  and  when  the  iron  or  steel  is  entirely  dissolved 
remove  the  stopper,  drop  a  small  piece  of  Na-jCOg  into  the  flask, 
and  close  it  with  a  solid  rubber  stopper.  Cool  the  flask  with  its 


i6o 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Cr  and  Al 
insoluble 
in  HC1. 


Separation 
of  Cr  and 
Al  from 
Feby 
NH4HS. 


Separation 
of  Cr  and 
Alby 
Dexter' s 
method. 


contents  as  quickly  as  possible,  and  dilute  the  solution  with  cold 
water  until  the  flask  is  three-fourths  full.  Add  BaCO3,*  shaking 
constantly  until  the  solution  appears  milky  with  the  excess  of 
BaCO3.  Loosen  the  stopper  to  allow  the  CO2  to  escape,  shake 
the  flask  at  intervals  for  several  hours,  and  allow  it  to  stand  over- 
night, the  stopper  being  pushed  well  into  the  neck.  The  precipi- 
tate will  consist  of  all  the  A12O3,  Cr2O3,  Fe2O3  from  the  solution,  as 
well  as  P2O5,  etc.,  and  the  graphite  and  silica  that  were  insoluble  in 
the  dilute  acid;  it  should  be  quite  white  from  the  excess  of  BaCO3 
added.  Filter  as  rapidly  as  possible,  wash  with  cold  water,  dis- 
solve on  the  filter  in  dilute  HC1,  allow  the  solution  to  run  into  a 
small  beaker,  clean  out  the  flask  with  the  same  acid,  and  wash  it 
and  the  filter  well  with  hot  water.  The  insoluble  matter  left  on 
the  filter  may  contain  some  chromium  and  aluminium  insoluble  in 
dilute  HC1,  and  usually  in  the  form  of  slag,  or  in  puddled  iron  as 
oxides.  This  may  be  ignited,  treated  with  HF1  and  H2SO4,  evapo- 
rated to  dryness,  fused  with  Na2CO3  and  KNO3,  and  the  Cr2O3  and 
A12O3  determined,  or  the  solution  of  the  fused  mass  in  dilute  HC1 
added  to  the  filtrate  from  the  insoluble  matter.  Boil  this  filtrate, 
add  a  slight  excess  of  H2SO4  to  precipitate  all  the  barium,  allow 
the  precipitate  of  BaSO4  to  settle,  filter,  and  wash  with  hot  water. 
Evaporate  the  filtrate  to  get  rid  of  the  excess  of  acid,  dilute  with 
cold  water,  add  sufficient  tartaric  or  citric  acid  to  hold  the  iron  in 
solution,  add  an  excess  of  NH4HO,  and  to  the  solution,  which 
should  be  perfectly  clear,  an  excess  of  NH4HS.  Allow  the  pre- 
cipitated FeS  to  settle,  filter,  wash  with  water  containing  NH4HS, 
evaporate  the  filtrate  to  dryness  in  a  large  platinum  crucible,  heat 
to  redness  to  volatilize  the  ammonium  salts,  and  burn  the  carbon 
formed  from  the  decomposition  of  the  tartaric  acid.  Fuse  the 
'residue  with  6  parts  Na2CO3  and  I  part  KNO3,  dissolve  out  in 
water,f  transfer  to  a  beaker,  add  2  or  3  grammes  KC1O3,  rinse  out 

*  See  page  44. 

f  If  the  fusion  or  its  concentrated  aqueous  solution  is  not  yellowish  in  color  there 
is  no  chromium  present. 


ANALYSIS   OF  IRON  AND   STEEL. 

the  crucible  with  HC1,  add  it  to  the  solution,  and  then  add  a  slight 
excess  of  HC1.  Evaporate  to  syrupy  consistency  on  the  water- 
bath,  adding  a  little  KC1O3  from  time  to  time  to  decompose  the 
excess  of  HCL*  Redissolve  in  water,  add  an  excess  of  carbonate 
of  ammonium  to  precipitate  the  A12O3,  and  boil  off  all  smell  of 
ammonia.  The  alumina  will  be  precipitated  as  phosphate,  wholly 
or  in  part,  if  the  sample  contains  phosphorus,  while  the  chromium 
is  in  solution  as  chromate  of  potassium  or  sodium.  Filter,  wash 
with  hot  water,  reserve  the  filtrate  and  washings,  redissolve  the 
precipitate  on  the  filter  in  HC1,  allowing  the  solution  to  run  into 
a  small  beaker,  evaporate  to  dryness  to  render  any  silica  insoluble, 
redissolve  in  HC1,  filter,  to  the  filtrate  add  excess  of  NH4HO  and 
NH4HS,  boil,  filter  on  a  small  ashless  filter,  wash  with  hot  water, 
ignite,  and  weigh  as  A12O3,  which  contains  53.31  per  cent.  Al. 
Acidulate  the  solution  containing  the  chromium  with  HC1,  heat  to 
decompose  the  excess  of  KC1O3,  add  a  little  alcohol,  and  evaporate 
to  dryness  to  render  silica  insoluble.  The  chromium  is  now  in  Determina- 
the  condition  of  Cr2O3;  redissolve  in  HC1,  dilute,  filter  off  any 
silica  that  may  be  present,  to  the  filtrate  add  an  excess  of  NH4HO, 
boil,  filter  on  a  small  ashless  filter,  wash  well  with  hot  water,  ignite, 
and  weigh  as  Cr2Q3,  which  contains  68.475  per  cent,  of  chromium. 
As  the  precipitates  of  A12O3  and  Cr2O3  may  both  contain  P2O5,  it  is 
necessary  to  fuse  each  of  them,  after  weighing,  with  a  little  Na2CO3, 
dissolve  in  water,  filter,  acidulate  with  HNO3,  and  determine  the 
P2O5  by  the  molybdate  method,  or  acidulate  with  HC1,  add  a  little  Separation 
citric  acid  and  magnesium  mixture,  and  determine  the  P2O5  as  0rCrjO8 
Mg2P2O7.  Calculate  the  amount  of  P2O5,  subtract  its  weight  from  P^*" 
that  of  the  A12O3  and  Cr2O3  respectively,  and  calculate  the  re- 
mainder to  Al  and  Cr,  as  directed  above. 

Instead  of  separating  the  aluminium  and  chromium  by  HC1 
and  KC1O3,  as  directed  above,  the  method  suggested  by  Genthf 
may  be  used,  which  is  as  follows :  Dissolve  in  water  the  fusion  of 

*  Dexter,  Pogg.  Annal.,  89,  142.  f  Chem.  News,  vi.  32. 


62  THE    CHEMICAL   ANALYSIS   OF  IRON. 

epara-         the  residue  from  the  volatilization  of  the  ammonium  salts  and  the 
Ai2o3         decomposition  of  the  tartaric  acid,  transfer  it  to  a  platinum  dish, 


add  a  few  grammes  of  nitrate  of  ammonium,  and  evaporate  down 
on  a  water-bath  until  the  solution  is  syrupy,  adding  NH4NO3  from 
time  to  time  until  the  addition  fails  to  produce  any  further  evolu- 
tion of  NH4HO  from  the  solution.  Add  a  little  carbonate  of 
ammonium  towards  the  end  of  the  operation,  and  when  the  solu- 
tion is  syrupy  and  smells  very  faintly  of  ammonia,  dilute  and 
filter  from  the  ALO,,  which  treat  as  directed  above.  To  the  fil- 

-       o' 

trate  add  a  strong  aqueous  solution  of  sulphurous  acid,  boil  off 
the  excess  of  SO2,  and  add  NH4HO  to  alkaline  reaction.  Boil, 
filter,  wash,  ignite,  and  weigh  the  Cr2O3,  which  must  be  tested  for 
etermma-  P2O5  as  above  directed.  To  determine  chromium  alone  in  iron 
alone.  or  steel,  treat  5  grammes  with  HC1,  precipitate  by  BaCO3,  filter 
and  wash  the  insoluble  matter  and  precipitate,  as  directed  above. 
Place  a  clean  beaker  under  the  funnel,  pierce  the  filter,  and  wash 
the  contents  into  the  beaker.  Clean  the  flask  and  filter  with  hot 
dilute  HC1,  and  wash  them  thoroughly  with  hot  water,  allowing 
all  the  acid  and  washings  to  run  into  the  beaker.  Add  enough 
HC1  to  dissolve  the  soluble  part  of  the  precipitate  (Fe2O3,  Cr2O3, 
A12O3,  BaCO3),  dilute,  boil,  and  precipitate  the  Cr2O3,  etc.,  with 
NH4HO.  Boil  off  all  smell  of  ammonia,  allow  the  precipitate  to 
settle,  and  wash  well  with  hot  water.  Dry,  and  transfer  the  pre- 
cipitate to  a  platinum  crucible,  carefully  separating  it  from  the 
filter,  ignite  the  filter,  and  add  its  ashes  to  the  precipitate  in  the 
crucible.  Before  heating  the  precipitate,  add  to  it  in  the  crucible 
3-6  grammes  Na2CO3  and  j£  gramme  KNO3  (with  pig-irons  it  is 
necessary  to  add  2-3  grammes  KNO3  to  oxidize  the  graphite), 
and  mix  thoroughly.  Heat  gradually  to  fusion,  and  finally  raise 
the  heat  until  all  the  KNO3  is  decomposed.  Cool,  treat  the  fused 
mass  with  hot  water,  filter  from  Fe2O3,  wash  well  with  hot  water, 
acidulate  the  filtrate  with  HC1,  and  evaporate  to  dryness  with 
a  little  alcohol.  Redissolve  in  HC1,  dilute,  filter  from  SiO2,  and 
in  the  filtrate  precipitate  the  Cr2O3  by  NH4HO.  Filter,  wash 


ANALYSIS   OF  IRON  AND   STEEL. 

thoroughly,  dry,  ignite,  and  weigh  as  Cr2O3.  This  precipitate 
may  contain  also  some  A12O3  and  P2O5,  which  must  be  separated 
in  very  accurate  determinations,  and  the  amounts  subtracted  from 
the  first  weight  of  Cr2O3. 

Volumetric  Method  for  Chromium. 

Galbraith*  has  suggested  a  rapid  method  for  the  determina- 
tion of  chromium  when  it  is  present  in  appreciable  amounts,  as  in 
chrome  steel  or  chrome  pig-iron.  Dissolve  1-3  grammes  of  the 
sample  in  dilute  H2SO4  (i  part  H2SO4  and  6  parts  water),  add 
permanganate  of  potassium  in  crystals  until  the  iron  is  all  oxi- 
dized and  the  liquid  is  quite  red  in  color,  then  add  as  much  more 
to  oxidize  the  chromium  to  CrO3.  Heat  the  solution  to  boiling, 
and  boil  until  the  permanganate  is  all  decomposed  and  there 
remains  a  precipitate  of  oxide  of  manganese.  Filter,  wash  with 
hot  water,  to  the  filtrate  add  a  measured  volume  of  standardized 
ferrous  sulphate,  and  determine  the  excess  of  ferrous  sulphate  by  a 
standard  solution  of  permanganate.  From  the  amount  of  ferrous 
sulphate  oxidized  by  the  CrO3  calculate  the  amount  of  Cr.  The 
reaction  is  6FeSO4  +  2CrO3  +  6H2SO4=3Fe2(SO4)3+Cr2(SO4)3  + 
6H2O,  or  i  equivalent  of  chromic  acid  will  oxidize  3  equivalents 
of  ferrous  sulphate  to  ferric  sulphate.  Therefore,  if  the  value  of 
the  permanganate  is  known  in  metallic  iron,  and  consequently  the 
value  of  the  ferrous  sulphate  (it  being  standardized  by  the  per- 
manganate) in  metallic  iron,  the  amount  of  chromium  is  calculated 
as  follows:  3  equiv.  Fe=i68  :  i  equiv.  0=52.13  ::  the  value 
of  the  ferrous  sulphate  oxidized  by  the  CrO3  in  Fe  :  its  value 
in  Cr ;  or  multiply  the  value  of  the  ferrous  sulphate  oxidized,  in 
Fe,  by  ^^-=,3103.  The  titration  is  effected  in  the  manner 
directed  for  the  determination  of  iron  in  iron  ores. 

*  Chem.  News,  xxxv.  151. 


i63 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


DETERMINATION    OF    ARSENIC. 

By  Precipitation  with  H2S. 

AsH3not  When    iron    or   steel    is    dissolved  in  dilute  HC1,  the  arsenic 

evolved  on 

dissolving    which   may  be  present,  according  to  Wohler,  is  not  evolved  as 
HCI  or       AsH3,  but  is  dissolved  as  AsCl5,  and,  unless  the  solution  is  very 

TT     C(~) 

acid,  upon  heating  it  a  white  flocculent  precipitate  of  ferric  arse- 
niate  is  formed.  It  is,  therefore,  possible  to  use  the  solution  in 
the  flask  from  the  determination  of  sulphur  in  steel  by  evolution 
(page  53  et  seq^)  for  the  estimation  of  arsenic.  If  this  is  not 
available  in  the  case  of  steel,  or  in  the  case  of  pig-iron  when 
the  residue  must  be  treated  for  S,  dissolve  10  grammes  of  drill- 
ings in  a  flask  in  40  c.c.  HCI  and  100  c.c.  water,  dilute  with 
hot  water  to  750  c.c.  and  pass  a  current  of  H2S  for  thirty  min- 
utes, fill  the  flask  to  the  neck  with  water,  cover  it  with  a  watch- 
glass,  and  stand  it  in  a  warm  place  overnight.  When  the  pre- 
cipitate has  settled  and  the  solution  smells  but  faintly  of  H2S, 
filter,  preferably  on  a  Gooch  crucible,  and  wash  with  cold  water. 
Transfer  the  filter  or  asbestos  felt,  with  the  precipitate,  to  a  small 
beaker,  pour  about  10-20  c.c.  KHS  solution  into  the  flask,  to 
dissolve  any  precipitate  that  may  have  adhered  to  the  sides,  and 
add  it  to  the  precipitate  in  the  beaker.  Digest  for  some  time 
at  a  gentle  heat,  filter,  wash  with  water  containing  a  little  KHS, 
acidulate  the  filtrate  slightly  with  HCI,  and  stand  it  in  a  warm 
place  until  the  smell  of  H2S  has  nearly  disappeared.  Filter  on 
a  Gooch  crucible,  wash  with  water,  dry  the  precipitate  and  felt 
(or  wash  with  alcohol),  extract  with  disulphide  of  carbon,  transfer 
the  felt  and  precipitate  to  a  small  beaker,  and  digest  with  HCI 
and  KC1O3.  Filter,  wash  with  as  little  water  as  possible,  add  a 
small  crystal  of  tartaric  acid  and  a  slight  excess  of  NH4HO, 
and  cool  the  solution.  If  the  solution  remains  clear,  as  it  will 
in  the  absence  of  tin,  add  5  c.c.  of  magnesium  mixture  and  J^ 
the  volume  of  the  solution  of  NH4HO.  Stir  the  solution  vigor- 
ously from  time  to  time,  keeping  it  cool  by  immersing  the  beaker 


ANALYSIS   OF  IRON  AND   STEEL. 

in  ice-water,  and  allow  it  to  stand  twelve  hours.  Filter  on  a 
Gooch  crucible,  wash  the  precipitate  of  Mg2(NH4)2As2O8-f  Aq 
with  the  ammonia- water  containing  nitrate  of  ammonium,  used 
for  washing  the  Mg2(NH4)2P2O8  (page  77),  dry  at  103°  C.  for  half 
an  hour,  then  increase  the  heat  very  gradually  to  redness,  and 
ignite  strongly  for  a  few  minutes.  Weigh  as  Mg2As2O7,  which 
contains  48.39  per  cent,  of  As.  If  the  sample  contains  tin,  the 
solution  obtained  above  will  become  cloudy  upon  the  addition 
of  NH4HO.  In  this  case  pass  a  current  of  H2S  through  the 
ammoniacal  solution  until  the  precipitated  oxide  of  tin  is  dis- 
solved, then  add  magnesium  mixture  and  ammonia,  and  pre- 
cipitate the  arsenic  as  directed  above. 

By  Distillation. 

Lundin  *  has  suggested  the  following  method  of  determining 
arsenic,  which  gives  very  good  results:  Dissolve  10  grammes 
of  drillings  in  a  large  beaker  in  HNO3,  1.2  sp.  gr.,  transfer  the 
solution  to  a  platinum  or  porcelain  dish,  add  50  c.c.  H2SO4, 
and  evaporate  down  until  copious  fumes  of  sulphuric  acid  are 
given  off.  Cool  the  dish,  add  50  c.c.  of  water,  and  evaporate 
again  until  the  excess  of  H2SO4  is  driven  off,  and  the  ferric 
sulphate  is  so  dry  that  it  can  be  readily  transferred  to  a  flask 
of  about  500  c.c.  capacity.  Add  to  the  mass  in  the  flask  15 
grammes  finely-powdered  ferrous  sulphate,  pour  in  150  c.c.  strong 
HC1,  and  close  the  flask  with  a  stopper  carrying  a  tube  bent 
twice  at  right  angles  and  connected  by  a  rubber  tube  with  a  50 
c.c.  pipette,  the  point  of  which  dips  about  y2  inch  (12  mm.)  into 
300  c.c.  of  water  in  a  beaker,  as  shown  in  Fig.  78.  Heat  the 
liquid  in  the  flask  gradually  until  it  boils,  and  continue  the  dis- 
tillation until  the  wide  part  of  the  burette  becomes  heated.  The 
arsenic  acid  in  the  solution  is  reduced  by  the  ferrous  sulphate, 
and,  in  the  strong  hydrochloric  acid  solution,  is  distilled  over 

*  Jern-Kontorets  Annaler,  1883,  P-  3^° ;  Chem.  News,  It.  115. 


i66 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


as   AsCl3.      About  half  an   hour   is    required  to   effect   this,   and 

when  the  wide  part  of  the  pipette  is  heated  remove  the  light, 
FlG  7s.  disconnect  the  pipette,  heat  the 

solution  in  the  beaker  to  about 
70°  C.,  and  pass  a  rapid  cur- 
rent of  H2S  through  it  until  it 
is  completely  saturated.  Re- 
move the  excess  of  H2S  by  a 
current  of  CO2,  and  when  the 
solution  smells  very  faintly  of 
H2S,  filter  off  the  yellow  pre- 
cipitate of  As2S3  in  a  Gooch 
crucible,  or  on  a  counterpoised 
filter,*  wash  with  water,  then 
with  alcohol,  then  with  pure 
"  disulphide  of  carbon,  dry  at 

1 00°    C.,  and    weigh   as   As2S3,   which  contains   60.98   per   cent, 

of  As. 


DETERMINATION    OF   ANTIMONY. 

Antimony  is  a  very  rare  constituent  of  iron  or  steel,  but  very 
minute  amounts  have  been  found  in  Spiegel.  To  determine  anti- 
mony, treat  10  grammes  of  the  drillings  as  directed  for  the  deter- 
mination of  arsenic  by  precipitation  with  H2S,  page  164.  Evap- 
orate off  the  excess  of  NH4HO  from  the  filtrate  from  the  Mg^ 
(NH4)2As2O8 -f- Aq,  add  a  slight  excess  of  HC1,  dilute  to  about 
300  c.c.  with  water,  and  pass  a  current  of  H2S  through  the  solu- 
tion. Expel  the  excess  of  H2S  by  a  current  of  CO2,  filter  on  a 
very  small  ashless  filter,  or  on  a  disk  of  paper  on  the  bottom  of  a 
Gooch  crucible,  wash  with  water,  and  dry  the  precipitate  and  filter. 
Separate  the  precipitate,  and  treat  the  filter  in  a  small  weighed  por- 


See  page  22. 


ANALYSIS   OF  IRON  AND   STEEL. 

celain  crucible  with  fuming  HNO3.  When  it  is  dissolved,  evap- 
orate down,  add  more  HNO3  if  necessary,  evaporate  to  dryness, 
and  heat  to  destroy  the  organic  matter.  When  the  residue  in  the 
crucible  is  quite  white,  allow  it  to  cool,  add  the  precipitate,  and 
treat  it  with  filming-  HNO3,  evaporate  down  to  dryness,  and  finally 
ignite  to  drive  off  the  sulphuric  acid  formed,  cool,  and  weigh  as 
Sb2O4,  which  contains  79.22  per  cent.  Sb.  When  tin  is  present,  and 
the  arsenic  has  been  precipitated  from  a  sulphide  of  ammonium 
solution,*  acidulate  the  filtrate  from  the  precipitate  of  Mg2(NH4)2 
As2O8  -f-  Aq  with  HC1,  and  when  the  solution  smells  but  faintly  of 
H2S,  filter  on  a  small  ashless  filter,  wash  with  water,  alcohol,  and 
finally  with  disulphide  of  carbon,  dry  the  precipitate  and  filter,  and 
treat  them  with  fuming  HNO3,  evaporate  down,  but  not  to  dryness, 
add  an  excess  of  dry  Na2CO3,  transfer  the  mass  to  a  silver  crucible, 
add  some  pure  fused  NaHO,  and  fuse  the  whole  for  some  minutes. 
Allow  the  crucible  to  cool,  dissolve  the  fused  mass  in  water,  trans- 
fer it  to  a  beaker,  and  add  %  the  volume  of  alcohol,  .83  sp.  gr. 
Stir  several  times,  and  allow  the  precipitate  of  metantimonate  of 
sodium  to  settle,  filter,  and  wash  with  a  solution  consisting  of 
equal  volumes  of  alcohol  and  water  containing  a  little  Na2CO3 
solution.  The  filtrate  contains  the  tin,  or  tin  and  arsenic.  Dis- 
solve the  precipitate  of  metantimonate  of  sodium  on  the  filter  in 
HC1  containing  tartaric  acid,  allow  the  solution  and  washings  to 
run  into  a  small  beaker,  dilute  to  about  300  c.c.,  and  precipitate 
the  sulphide  of  antimony  by  H2S.  Filter  off,  and  determine  the 
antimony  as  Sb2O4  as  above  directed. 


DETERMINATION    OF   TIN. 

Tin  is  a  most  unusual  constituent  of  steel  or  iron,  but  has  been 
found  in  the  former  in  cases  where  scrap  from  tinned  iron,  from 

*  The  precipitated   sulphides   from   acidulated   KHS   solution   may  be   treated 
directly  in  this  way  without  precipitating  the  arsenic  as  Mg2(NH4)2As2O8  -(-  Aq. 


THE    CHEMICAL   ANALYSIS   OF  IRON. 

which  the  tin  has  been  removed  by  a  chemical  process,  has  been 
melted  in  the  open-hearth  furnace  as  a  portion  of  the  charge.  Pro- 
ceed as  in  the  determination  of  antimony,  until  the  sulphides  from 
the  acidulation  of  the  KHS  solution  have  been  filtered  on  a  small 
ashless  filter  and  washed  thoroughly  with  a  solution  of  acetate  of 
ammonium  made  slightly  acid  with  acetic  acid.  It  is  not  possible 
to  wash  the  precipitate  with  water,  as  the  sulphide  of  tin  has  a 
strong  tendency,  under  these  circumstances,  to  pass  through  the 
filter.  Dry  the  precipitate  and  filter,  transfer  the  precipitate  to  a 
weighed  porcelain  crucible,  burn  the  filter,  and  add  its  ash  to  the 
precipitate,  add  a  little  sulphur,  and  ignite  in  a  current  of  H2S,  as 
directed  for  the  determination  of  manganese  as  MnS,  page  94. 
Any  arsenic  present  will  be  volatilized,  but  it  is  not  possible  to 
weigh  the  tin  as  sulphide,  as  its  composition  is  not  constant. 
Heat  the  crucible  carefully,  and  roast  the  precipitate  with  access 
of  air,  heat  it  strongly  two  or  three  times  with  carbonate  of  ammo- 
nium to  volatilize  any  sulphuric  acid  that  may  have  been  formed, 
cool,  and  weigh  as  SnO2,  which  contains  78.67  per  cent.  Sn. 


DETERMINATION    OF   TUNGSTEN. 

Dissolve  I  to  10  grammes  of  the  drillings  in  HNO3,  1.2  sp.  gr., 
evaporate  to  dryness  in  the  air-bath,  redissolve  in  HC1,  dilute 
slightly,  and  boil  for  some  time.  The  tungstic  acid  is  deposited 
as  a  yellowish  powder.  Dilute,  filter,  wash  with  hot  water  con- 
taining a  little  HC1,  and  finally  with  alcohol  and  water.  The  pre- 
cipitate consists  of  WO3  mixed  with  more  or  less  SiO2,  graphite, 
and  perhaps  a  little  Fe2O3,  TiO2,  etc.  Dry  and  ignite  the  filter 
and  precipitate,  and  burn  off  the  carbon.  Allow  the  crucible  to 
cool,  moisten  the  precipitate  with  water,  add  a  little  H2SO4  and  an 
excess  of  HF1.  Evaporate  to  dryness  under  a  hood,  and  ignite 
to  drive  off  the  H2SO4.  Fuse  the  residue  with  5  times  its  weight 


ANALYSIS   OF  IRON  AND   STEEL. 

of  Na2CO3,  allow  it  to  cool,  dissolve  in  water,  filter  from  any  in- 
soluble matter,  and  wash  with  water  containing  a  little  Na2CO3. 
The  filtrate  contains  all  the  tungsten,  as  tungstate  of  sodium. 
Nearly  neutralize  with  HNO3,  and  boil  off  the  CO2,  allow  the 
solution  .to  cool  slightly,  and  add  a  faint  but  distinct  excess  of 
HNO3.  Add  an  excess  of  mercurous  nitrate,*  and  then  mercuric 
oxide  diffused  in  water,*  until  the  free  acid  is  all  neutralized.  The 
tungsten  is  all  precipitated  as  mercurous  tungstate,  and  can  be 
washed  perfectly  free  from  all  sodium  salts  with  hot  water.  The 
method  of  neutralizing  the  solution  with  mercuric  oxide  is  due  to 
Dr.  Gibbs,f  and  makes  of  a  very  uncertain  method  an  extremely 
accurate  one.  Allow  the  precipitate  to  settle,  filter  on  an  ashless 
filter,  wash  with  hot  water,  and  dry  the  filter  and  precipitate. 
Separate  the  precipitate  from  the  filter,  burn  the  filter  in  a  platinum 
crucible,  add  the  precipitate,  and  heat  it  under  a  hood  with  a  good 
draft,  increasing  the  heat  gradually  to  a  bright  red.  The  mercury 
volatilizes,  and  there  remains  only  WO3.  Cool,  and  weigh  as 
WO3,  which  contains  79.31  per  cent,  of  W. 

Schoffer  %  has  suggested  the  method  of  dissolving  the  steel  or 
iron  in  the  double  chloride  of  copper  and  ammonium.  The  tung- 
sten remains  in  the  insoluble  matter,  which  he  filters  off,  ignites, 
fuses  with  Na2CO3,  and  finally  precipitates  as  WO3  with  mercurous 
nitrate.  This  method  has  no  advantage  over  the  one  first  given, 
and  has  the  disadvantage  of  contaminating  the  WO3  with  P2O5,  and 
also  with  any  chromium  and  arsenic  which  may  be  in  the  sample. 


DETERMINATION    OF    VANADIUM. 

Vanadium  is  occasionally  found  in  pig-iron,  and  may  be  deter- 
mined with  great  accuracy  by  the  following  method:  Treat  5 
grammes  of  the  drillings  with  50  c.c.  HNO3,  1.2  sp.  gr.,  in  a  No.  4 

*See  page  49.  f  Amer.  Chem.  Jour.,  v.  373.  J  Chem.  News,  xli.  31. 

12 


THE   CHEMICAL   ANALYSIS   OF  IRON. 

beaker.  When  all  action  has  ceased,  transfer  the  liquid  to  a 
porcelain  dish,  evaporate  to  dryness,  and  heat  at  a  gradually  in- 
creasing temperature  over  a  Bunsen  burner  until  the  nitrates  are 
nearly  all  decomposed  and  the  mass  separates  easily  from  the 
bottom  and  sides  of  the  dish.  Transfer  the  cooled  mass  to  a  por- 
celain or  agate  mortar,  and  grind  it  thoroughly  with  30  grammes 
of  dry  Na2CO3  and  3  grammes  of  NaNO3.  Transfer  to  a  large 
platinum  crucible,  and  fuse  well  for  about  an  hour  at  a  high  tem- 
perature. Run  the  fused  mass  well  up  on  the  sides  of  the  cruci- 
ble, allow  it  to  cool,  dissolve  in  hot  water,  and  filter.  Dilute  the 
filtrate  to  about  600  c.c.,  and  add  nitric  acid  carefully  to  get  rid  of 
the  carbonic  acid.  Boil  off  the  latter,  but  be  careful  to  keep  the 
solution  always  slightly  alkaline.  Add  nitric  acid  drop  by  drop 
until  the  solution  is  just  acid,  then  add  a  few  drops  of  carbonate 
of  sodium  solution  to  render  the  solution  faintly  but  decidedly 
alkaline,  boil  for  a  few  minutes,  and  filter.  To  the  filtrate  add  a  few 
drops  of  nitric  acid  to  make  it  faintly  acid,  when  the  appearance 

indication  of  a  yellowish  coloration  is  an  indication  of  the  presence  of  vanadic 
Vz  5'  acid.  Add  to  the  solution  a  few  c.c.  of  mercurous  nitrate,*  and 

Precipitation  then  an  excess  of  mercuric  oxide  in  water,*  to  render  the  solution 

as  mercu-  1    ,  .  -  -  ...  r*        1 1        i 

rousvana-  neutral  f  and  insure  the  complete  precipitation  of  all  the  mer- 
curous vanadate.  With  the  mercurous  vanadate  are  precipitated 
also  all  the  phosphoric,  chromic,  tungstic,  and  molybdic  acids  as 
mercurous  salts.  Heat  to  boiling,  filter,  and  wash  the  precipitate. 
Dry  it,  separate  the  paper,  burn  it  in  a  platinum  crucible,  add  the 
precipitate,  heat  carefully  to  expel  the  mercury,  and  finally  heat 
to  full  redness.  Fuse  the  brownish-red  mass  remaining  in  the 
crucible  with  a  small  amount  of  Na2CO3  and  a  pinch  of  NaNO3, 
dissolve  the  cooled  mass  in  a  small  amount  of  water,  and  filter 
Precipitation  into  3.  small  beaker.  Add  to  the  solution  pure  chloride  of  ammo- 


as  vana-  .  , 

date  of       nium  in  excess  (about  3.5  grammes  to  each   10  c.c.  of  solution), 

ammo- 
nium. 


and  allow  it  to  stand  for  some  time,  stirring  occasionally.     Vana- 


See  page  49.  f  Am.  Chem.  Jour.,  v.  373. 


ANALYSIS   OF  IRON  AND   STEEL.  !7I 

date  of  ammonium,  insoluble  in  a  saturated  solution  of  chloride 
of  ammonium,  separates  out  as  a  white  powder.  It  is  necessary  Precautions, 
to  keep  the  solution  decidedly  alkaline,  and  a  drop  or  two  of  am- 
monia must  be  added  from  time  to  time.  The  appearance  of  the 
faintest  yellowish  tint  to  the  solution  is  evidence  that  the  solution 
has  become  slightly  acid,  and  this  must  be  corrected  or  the  result 
will  be  too  low.  Filter  on  a  small  ashless  filter,  wash  first  with  a 
saturated  solution  of  chloride  of  ammonium  containing  a  drop  or 
two  of  ammonia,  and  then  with  alcohol.  Dry,  ignite,  moisten  with 
a  drop  or  two  of  nitric  acid,  ignite,  and  weigh  as  V2O5,  which 
contains  56.16  per  cent,  of  vanadium. 


METHODS  FOR  THE  ANALYSIS 


OF 


IRON  ORES 


Method  of  A    FEW   words    in    regard   to    the    proper    method  of   taking 

sampling 

iron  ores,  samples  of  iron  ores  may  not  be  amiss,  for  unless  the  sample 
truly  represents  the  lot  from  which  it  is  taken,  the  subsequent 
work  of  the  analyst  is  useless,  if  not  misleading. 

In  drawing  a  sample,  note  carefully  the  relative  amounts  of 
fine  ore  and  lumps  in  the  lot  to  be  sampled,  and  see  that  this 
proportion  be  observed  in  the  whole  amount  taken.  A  small 
trowel  may  be  used  for  taking  the  fine  ore,  and  only  about  a 
teaspoonful  should  be  picked  up  at  one  time.  In  taking  pieces 
from  the  lumps,  it  will  never  do  to  merely  chip  the  outside,  but 
each  lump  as  selected  should  be  broken  and  chippings  taken 
from  both  the  inside  and  the  outside,  and  no  piece  taken  should 
be  larger  than  a  cherry.  In  sampling  from  cars  or  wagons  these 
points  should  be  observed  in  each  car  or  wagon,  for  it  is  rarely 
the  case  that  the  ore  even  from  one  mine  is  so  uniform  as  to 
render  this  precaution  unnecessary.  In  some  cases  the  lumps 
are  covered  with  dirt  or  gangue,  making  the  outside  of  the  lump 
poorer  in  iron  than  the  inside,  and  on  the  other  hand  the  lumps 
are  merely  masses  of  dirt  coated  with  ore.  Then  the  fine  stuff 
may  be  much  richer  than  the  lumps,  or  it  may  be  merely  dirt  or 
gangue,  while  it  almost  always  contains  more  hygroscopic  water 
Preserving  than  the  lumps.  The  sample  should  be  taken  in  tin  cans  with 

close-fitting  lids,  and  the  amount  should  be  proportioned  to  the 
172 


ANALYSIS  OF  IRON  ORES. 

size  of  the  lot  sampled.     Two  pounds  to  ten  tons  is  a  good  rule 
for  large  lots. 

DETERMINATION    OF   HYGROSCOPIC   WATER. 

Break,  the  sample  down  quickly  to  about  pea  size,  mix  thor- 
oughly in  a  large  glazed  earthenware  or  metal  dish,  and  weigh  out 
from  T/2,  to  I  kilo,  into  a  copper  box  about  \y2  inches  (114  mm.) 
long,  3^  inches  (95  mm.)  wide,  and  ij^  inches  (38  mm.)  deep, 
and  dry  in  a  water-  or  air-bath  at  100°  C.  for  at  least  twelve  hours, 
or  until  it  ceases  to  lose  weight.  Fig.  79  shows  a  convenient  form 


FIG.  79. 


173 


of  water-bath.  The  boxes  are  numbered,  and  each  one  is  pro- 
vided with  a  counterpoise  stamped  with  the  same  number  as  the 
box,  to  facilitate  the  weighing.  When  a  supply  of  water  is  not 
available  to  run  the  constant  level  shown  in  Fig.  79,  the  device, 


174 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


Device  for 
constant 
level. 


Balance  for 
weighing 
samples. 


on  the  principle  of  Marriott's  flask,  as  shown  in  Fig.  71,  page  143, 
may  be  used.  The  position  of  the  end  b  of  the  tube  a  fixes  the 
level  of  the  water  in  the  bath. 

A  balance  sensitive  to  .1  gramme  is  sufficiently  accurate  for 
weighing  these  samples.  The  loss  of  weight  in  grammes  divided 
by  5,  when  T/2  kilo,  of  ore  was  originally  used,  gives  the  percentage 
of  hygroscopic  water  in  the  sample.  Grind  the  dried  sample  very 
fine,  mix  it  well,  heat  as  much  of  it  as  may  be  required  for  the 
analysis  in  the  water-bath,  and  put  it  while  still  hot  into  a  per- 
fectly dry,  glass-stoppered  bottle. 


Residue  in- 
soluble 
in  HC1. 


Treatment 
of  the  ore. 


Treatment 
of  the  in- 
soluble 
residue 
by  H2S04 
and  HF1. 


DETERMINATION    OF   TOTAL   IRON. 

Very  few  iron  ores  are  completely  decomposed  by  hydro- 
chloric acid,  the  insoluble  residue  usually  containing  more  or  less 
iron,  as  silicate,  titaniferous  iron,  etc.  The  disregard  of  this  fact 
may  occasion  grave  errors  in  the  determination  of  iron,  and, 
unless  a  previous  examination  has  shown  the  absence  of  iron  in 
the  insoluble  residue,  it  is  best  to  proceed  as  follows  :  Weigh  I 
gramme  of  the  finely-ground  sample  into  a  No.  I  beaker,  add  10 
c.c.  HC1,  and  digest  it  in  the  sand-bath  until  the  residue  appears 
quite  white  and  flotant,  or  until  the  acid  appears  to  have  no 
further  action.  When  the  ore  contains  carbonaceous  matter,  add 
a  little  KC1O3.  Wash  off  the  watch-glass  with  a  fine  jet  of  water, 
remove  it,  and  evaporate  to  dryness  in  the  air-bath.  Redissolve 
in  about  5  c.c.  HC1,  dilute  with  10  c.c.  water,  allow  to  settle,  and 
decant  the  clear  liquid  into  a  flask  (B,  Fig.  81)  of  about  50  to  75 
c.c.  capacity.  Transfer  the  residue  to  a  small  filter,  fitted  in  a 
funnel  placed  in  the  neck  of  the  flask,  with  as  little  water  as  pos- 
sible, and  wash  with  cold  water  from  a  fine  jet.  Transfer  the  filter 
to  a  small  platinum  crucible,  burn  it  off,  allow  the  crucible  to  cool, 
and  pour  on  the  residue  20  or  30  drops  of  H2SO4  and  about  twice 
as  much  HF1.  Heat  carefully,  and,  if  the  residue  is  dissolved,  evap- 


ANALYSIS  OF  IRON  ORES.  ^5 

orate  off  the  HF1,  allow  the  liquid  to  cool,  and  dilute  slightly, 
when  it  will  be  ready  to  add  to  the  solution  in  the  flask,  which 
shall  have  been  deoxidized  in  the  mean  time  by  one  of  the  methods 
explained  farther  on. 

Occasionally  this  treatment  fails  to  decompose  the  insoluble 
residue,  in  which  case  it  is  necessary  to  heat  the  crucible  until 
the  greater  part  of  the  H2SO4  shall  have  been  driven  off;  then 
add  about  .5  gramme  KHSO4,  and  heat  gradually  until  the  Treatment 

with 

KHSO4  is  quite  liquid  and  fumes  of  SO3  are  given  off  whenever     KHso4. 
the  lid  of  the  crucible  is  raised.     When  all  the  black  specks  have 
disappeared,  allow  the  crucible  to  cool,  and  dissolve  the  salt  in  the 
crucible  with  hot  water  and  a  few  drops  of  HC1. 

Several  methods  are  used  for  the  deoxidation  of  the  solution 
of  ferric  chloride,  but  the  one  in  general  use  is  by  adding  metallic 
zinc  to  the  solution.  The  iron  is  deoxidized  according  to  the 
reaction  Fe2Cl6  +  Zn  =  2FeCl2  +  ZnQ2,  while  the  excess  of  HC1 
is  decomposed  and  hydrogen  liberated,  2HCl  +  Zn=ZnCl2+2H. 
As  all  zinc  contains  a  small  amount  of  iron,  the  amount  added  to 
the  solution  should  be  roughly  weighed.  Add  then  to  the  solu-  D^idba' 
tion  in  the  flask  3  grammes  of  granulated  zinc,*  and,  when  the  metallic 

zinc. 

evolution  of  hydrogen  has  somewhat  slackened,  heat  the  flask 
slightly.  The  neck  of  the  flask  is  closed  by  a  small  funnel,  which 
allows  the  hydrogen  to  escape  while  the  liquid  is  caught  on  the 
funnel  and  falls  back  into  the  flask.  It  sometimes  happens  as  the 
solution  becomes  neutralized  that  a  basic  salt  of  peroxide  of  iron 
is  thrown  down,  giving  the  solution  a  reddish  color ;  in  this  case 
add  a  few  drops  of  HC1,  and  when  the  solution  finally  becomes 
colorless  add  a  few  drops  more  of  HC1.  If  this  fails  to  produce  a  End  of  the 

reaction. 

yellowish  coloration,  the  solution  may  be  considered  deoxidized. 

Pour  in  through  the  funnel  the  solution  of  the  residue  insoluble  in  Final  addi- 
tion of 

HC1,  and  add  gradually  a  mixture  of  10  c.c.  H2SO4  and  20  c.c.     H,so4. 
H2O.     This  addition  of  H2SO4  is  a  very  necessary  part  of  the 

*  See  page  50. 


THE    CHEMICAL   ANALYSIS  OF  IRON. 

operation,  for  it  not  only  serves  to  dissolve  the  remainder  of  the 
zinc  which  is  unacted  on  when  the  deoxidation  is  complete,  but  it 
supplies  the  proper  amount  of  sulphate  of  zinc  and  iron,  which 
makes  the  end  reaction  with  permanganate  of  potassium  as  sharp 
as  if  no  HC1  were  present  in  the  solution.  As  soon  as  all  the 
zinc  is  dissolved,  wash  down  the  funnel  inside  and  out  and  the 
neck  of  the  flask  with  a  fine  jet  of  water,  filling  the  flask  almost 
full,  cool  the  flask  in  water,  and  when  the  solution  is  quite  cold 
transfer  it  to  a  large  white  dish  of  about  1500  c.c.  capacity  (see  A, 
Fig.  8 1,  page  185).  Wash  the  flask  and  funnel  well  with  cold 
water,  pour  the  rinsing  into  the  dish,  and  make  the  solution  up  to 
about  1000  c.c.  Run  in  from  a  burette  a  standard  solution  of 

perman- 

ganateso-  permanganate  of  potassium  (Marguerite's  method),  the  value  of 
which  has  been  carefully  determined  by  one  of  the  methods  de- 
scribed farther  on.  At  first  the  color  of  the  permanganate  is 
destroyed  almost  as  soon  as  it  touches  the  liquid  in  the  dish,  which 
should  be  stirred  carefully  with  a  glass  rod.  The  permanganate 
should  be  added  more  and  more  slowly  until  towards  the  end  of 
the  operation  it  is  added  only  drop  by  drop.  The  liquid  in  the 
dish  gradually  assumes  a  yellowish  tint,  which  is  deeper  the 
larger  the  amount  of  iron  in  the  ore.  Finally  a  drop  of  the  per- 
manganate seems  to  destroy  the  yellow  color,  and  the  next  drop 
gives  the  liquid  a  very  faint  pink  tinge.  This  is  the  end  of  the 
reaction.  Take  the  reading  of  the  burette,  and  then  add  another 
drop,  which  will  cause  the  solution  to  become  decidedly  pink  in 
color.  The  number  of  c.c.  of  the  standard  solution  used  when 
the  reading  was  taken,  less  a  small  correction  noted  on  page  181, 
multiplied  by  the  value  of  I  c.c.,  gives  the  amount  of  metallic  iron 
in  the  ore. 

•itration  When  using  a  standard  solution  of  bichromate  of  potassium 

chromate     (Penny's  method),  the  end  reaction  is  not  rendered  apparent  by  a 

of  potas- 

slum.  change  in  the  color  of  the  solution,  but  the  presence  or  absence 
of  ferrous  salt  in  the  solution  is  determined  by  taking  a  drop  from 
the  dish  on  the  end  of  the  stirring-rod  and  allowing  it  to  run  into 


ANALYSIS   OF  IRON  ORES. 

a  drop  of  a  dilute,  freshly-made  solution, of  ferricyanide  of  potas- 
sium placed  on  a  white  tile  or  capsule.  Dissolve  a  very  small 
crystal  of  ferricyanide  of  potassium  in  a  few  c.c.  of  water,  and 
place  a  number  of  drops  of  the  solution  on  a  white  tile  or  on  a 
flat-bottomed  capsule.  Run  the  carefully  standardized  solution 
of  bichromate  of  potassium  from  the  burette  into  the  deoxidized 
iron  solution  previously  placed  in  a  white  dish.  The  solution,  at 
first  colorless,  changes  gradually  to  a  decided  chrome-green  from 
the  reduction  of  the  chromic  acid.  Test  the  progress  of  the  oxi- 
dation of  the  iron  solution  by  transferring  a  drop  of  it  on  the  end 
of  the  stirring-rod  to  one  of  the  drops  of  ferricyanide.  As  the 
blue  color  produced  becomes  less  intense,  add  the  bichromate 
more  slowly  and  make  the  test  more  frequently,  towards  the  end 
of  the  operation  after  the  addition  of  each  drop  of  bichromate. 
When,  finally,  no  color  appears  in  the  test-drops,  even  after  the  End  of  the 
lapse  of  several  moments,  the  oxidation  of  the  ferrous  salt  is  com- 
plete, and  the  amount  of  bichromate  used,  less  a  small  correction 
noted  on  page  181,  is  the  measure  of  the  amount  of  iron  in  the 
ore.  The  ferricyanide  of  potassium  employed  must,  of  course,  Purity  of 
be  perfectly  free  from  ferrocyanide :  it  may  be  tested  by  adding  amde. 
a  drop  of  ferric  chloride  solution  to  one  of  the  drops  of  ferri- 
cyanide solution,  the  absence  of  any  resulting  blue  color  in  the 
test-drops  being  proof  of  the  purity  of  the  ferricyanide.  As 
towards  the  end  of  the  operation  the  frequent  tests  become  rather 
tedious,  some  analysts  prefer  to  make  the  determinations  in  dupli-  Duplicate 

determina- 

cate,  using  the  first  to  get  an  approximate  result  rather  quickly,     tions. 
and  the  second  to  get  the  exact  result  after  running  in  at  once  a 
little  less  than  the  amount  of  bichromate  shown  to  be  necessary 
by  the  first  test. 

When  the  ore  is  completely  decomposed  by  HC1,  a  separate  Treatmentof 

ores  com- 
treatment  of  the   residue   is    unnecessary,   and   the   ore   may  be     pieteiy  de- 
weighed   at   once   into  the   flask  and   treated  with    10   c.c.    HC1        " 
and  a  little   KC1O3  when  organic  matter  is  present.     When  the 
ore  is  completely  decomposed,  and  any  little  Cl  from  the  KC1O3 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


tion  by 

NH4Hso3. 
Necessary 

in  the  pres- 

ence  of 


Details 

of  the 

method. 


by  SnCl2. 


driven  off,  add  30  c.c.  of  water,  and  proceed  with  the  deoxidation 
as  previously  described. 

Instead  of  deoxidizing  the  solution  of  ferric  chloride  by  zinc,  it 
may  be  deoxidized  by  a  solution  of  bisulphite  of  ammonium.  In 
fact,  the  deoxidation  by  zinc  is  not  practicable  in  ores  containing 
much  TiO2,  for  the  TiO2  is  reduced  by  metallic  zinc  to  Ti2O3,  im- 
parting a  purple  or  blue  color  to  the  solution,  and  acting  like  a 
solution  of  ferrous  salt  on  the  standard  solution  of  permanganate. 
In  deoxidizing  a  solution  of  ferric  chloride  by  this  method  it 
should  be  placed  in  a  flask  of  120  c.c.  capacity,  and  two  or  three 
small  spirals  of  platinum  wire  added  to  facilitate  the  subsequent 
boiling.  Add  cautiously  to  the  solution  (which  should  not  exceed 
40  c.c.  in  volume)  enough  ammonia  to  produce  a  slight  permanent 
precipitate  of  ferric  hydrate,  which  remains  even  after  vigorous 
shaking.  Add  now  5  c.c.  of  a  strong  solution  of  NH4HSO3,* 
shake  vigorously,  and  warm  the  flask  gently.  As  the  color  of 
the  solution  —  at  first  a  deep  red  —  fades,  increase  the  heat,  and 
finally  heat  to  boiling.  When  the  solution  is  quite  colorless,  add 
to  it  the  solution  of  the  residue  and  10  c.c.  H2SO4  mixed  with 
20  c.c.  H2O.  Boil  the  solution  until  all  the  sulphurous  acid  is 
driven  off.  The  pieces  of  platinum  wire  will  cause  the  gas  to  be 
given  off  freely  at  the  bottom  of  the  flask,  and  the  funnel  in  the 
neck  will  prevent  the  access  of  air  and  the  loss  of  any  portion 
of  the  solution.  When  the  escaping  steam  no  longer  smells  of 
SO2,  place  the  flask  in  cold  water,  wash  down  the  funnel  and 
the  neck  of  the  flask,  filling  the  latter  quite  full  of  water,  and 
when  the  solution  is  quite  cold  transfer  it  to  a  dish  and  titrate 
with  a  standard  solution. 

^  third  method  of  deoxidizing  the  solution  of  ferric  chloride 
is  sometimes  used,  in  which  the  reducing  agent  is  a  solution  of 
stannous  chloride.  The  details  of  the  method  are  as  follows  :  f 
Dissolve  I  gramme  of  the  ore  in  30  c.c.  strong  HC1  (if  neces- 


See  page  37. 


f  Stock  and  Jack,  Chem.  News,  xxxi.  63. 


ANALYSIS  OF  IRON  ORES. 

sary,  filter  off,  ignite,  and  fuse  the  residue  with  a  little  Na2CO3, 
dissolve  in  water  and  HC1,  and  add  to  the  main  solution),  transfer 
to  a  flask,  dilute  to  500  c.c.,  and  heat  to  boiling.  Add  to  the 
boiling  solution,  very  cautiously,  a  clear  acid  solution  of  SnCl2 
containing  about  10  grammes  Sn  to  the  litre.  When  the  yellow 
color  of  the  ferric  chloride  solution  becomes  very  faint,  add  the 
SnCl2  solution  drop  by  drop,  and  test  the  former  for  ferric  salt 
by  transferring  a  drop  of  it  on  the  end  of  a  rod  to  a  drop  of  a 
dilute  fresh  solution  of  sulphocyanate  of  potassium  on  a  white 
tile  or  capsule.  A  number  of  drops  of  the  sulphocyanate  should 
be  placed  on  the  surface  of  the  tile  or  capsule,  so  that  the  tests 
may  be  made  frequently,  and  without  any  delay,  during  the 
reduction.  After  each  addition  of  the  SnCL  solution  the  liquid  Test  for  the 

end  of  the 

in  the  flask  should  be  allowed  to  boil  for  a  few  moments,  then  reduction. 
a  drop  taken  from  it  on  a  rod  should  be  transferred  quickly  to 
one  of  the  drops  of  sulphocyanate.  When  the  color  produced 
in  the  sulphocyanate  is  only  a  faint  pink  the  deoxidation  may 
be  considered  perfect.  It  is,  however,  possible  that  an  excess 
of  SnCl2  may  have  been  added,  and  it  is  therefore  necessary 
to  test  the  effect  of  the  addition  of  the  first  two  or  three  drops 
of  the  standard  ^solution  of  bichromate  of  potassium  (perman- 
ganate cannot  be  used)  to  the  liquid.  The  reading  of  the  burette  Test  for 

excess  of 

having  been  observed,  transfer  two  or  three  drops  of  the  bichro-  sncuso- 
mate  solution  to  the  liquid  in  the  flask,  and  test  it  again  with 
the  sulphocyanate.  If  the  result  is  a  decided  increase  in  the 
intensity  of  the  coloration,  transfer  the  solution  to  the  dish  and 
finish  the  titration  with  the  bichromate  solution.  The  reduc- 
tion of  the  ferric  chloride  solution  is  expressed  by  the  formula 
Fe2Cl6+  SnCl2=2FeCl2-f  SnQ4. 

Methods  for  Standardizing  the  Solutions. 
It  is  of  the  utmost  importance  that  the  value  of  the  standard  Conditions 

affecting 

solution  employed  should  be  determined  with  the  greatest  accu-     the  accu- 

racy  of 

racy  if  the  results  obtained  by  its  use  are  to  be  anything  but  mere     the  vaiu- 


i8o 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


ation  of 
the  stand- 
ard. 


Preparation 
of  ferric 
chloride 
solution. 


Preserva- 
tion of 
the  solu- 
tion. 


Determina- 
tion of  the 
strength 
of  the 
ferric 
chloride 
solution. 


approximations  to  the  truth.  To  do  this,  not  only  should  the 
reagents  employed  be  pure,  but  the  conditions  under  which  the 
standard  is  fixed  should  be,  as  nearly  as  practicable,  those  under 
which  it  is  employed  in  actual  use.  The  conditions  referred  to 
are  not  only  those  of  temperature,  dilution,  etc.,  but  of  the  actual 
chemical  composition  of  the  liquid  acted  on  by  the  standard  solu- 
tion by  which  its  value  is  determined. 

The  best  reagent  to  employ  is  a  solution  of  ferric  chloride 
of  known  strength.  To  prepare  this,  dissolve  100  grammes  of 
wrought  iron  (free  from  manganese  and  arsenic,  and  in  which  the 
phosphorus  has  been  accurately  determined)  in  nitric  acid,  evapo- 
rate to  dryness  in  a  capsule,  and  heat  until  the  nitrate  of  iron  is 
largely  decomposed  and  the  mass  separates  easily  from  the  bottom 
and  sides  of  the  capsule.  Transfer  to  a  piece  of  platinum-foil 
with  the  edges  turned  up,  and  heat  for  some  time  in  a  muffle 
at  a  very  high  temperature,  or  heat  it,  a  portion  at  a  time,  in  a 
crucible  at  the  highest  temperature  obtainable  by  a  blast-lamp. 
Grind  the  entire  mass  very  fine  in  an  agate  mortar,  dissolve  in 
HC1,  evaporate  to  dryness,  redissolve  in  dilute  HC1,  filter  to  get 
rid  of  SiO2,  and  dilute  the  solution  to  about  4  litres.  Twenty  c.c. 
of  this  solution  will  contain  about  .5  gramme  Fe,  and  it  may  be 
kept  indefinitely  in  a  glass-stoppered  bottle  sealed  with  paraffine, 
or  after  being  thoroughly  mixed  it  may  be  preserved  in  a  number 
of  smaller  bottles  properly  secured. 

Wash  out  and  dry  thoroughly  three  of  the  small  flasks  used 
for  deoxidizing  the  solutions  of  the  ores,  weigh  them  to  within 
i  mg.,  and  measure  into  each  a  portion  of  the  ferric  chloride 
solution  ranging  from  15  to  25  c.c.  in  volume.  Weigh  the  flasks 
and  their  contents ;  the  differences  between  the  first  and  second 
weights  are  the  weights  of  the  ferric  chloride  solution  taken. 
Transfer  the  solution  carefully  from  each  flask  to  a  platinum  dish, 
dilute,  boil,  precipitate  by  NH4HO,  filter,  wash,  dry,  ignite,  and 
weigh  the  precipitate  with  the  precautions  mentioned  farther 
on.  The  precipitate  is  Fe2O3 -j- P2O5.  Subtract  from  this  weight 


ANALYSIS   OF  IKON  ORES.  jg 

the  amount  of  P2O5  in  this  weight  of  the  material,  and  the  remain- 
der will  be  the  weight  of  Fe2O3  in  the  amount  of  solution  used. 
Suppose,  for  example,  that  the  original  iron  contained  .1  per  cent.  Example 
P,  this  would  be  equivalent  to  0.229  per  cent.  P2O5,  but,  as  the  iron  ttmte  the 
has  been  oxidized  to  Fe2O3,  the  percentage  of  P2O5  in  the  iron  as 
oxide  would  be  only  -^  as  great  as  in  the  iron  itself,  the  weight  as 
oxide  being  ty  as  great  as  it  was  as  Fe.  Therefore  multiply  .229 
per  cent,  by  .7  for  the  percentage  of  P2O5  in  the  Fe2O3,  which  gives 
.16  per  cent.  P2O6.  If  we  further  suppose  that  the  weight  of 
Fe2O3 -f  P2O5  obtained  was  .8131  gramme,  .16  per  cent,  of  this 
would  be  .0013  gramme,  the  weight  of  P2O5  in  the  precipitate, 
and  .8131 — .00 1 3  =  .8 1 18  gramme,  the  weight  of  Fe2O3  in  the 
amount  of  solution  taken.  Divide  this  weight  by  the  weight  of 
the  solution,  and  the  result  is  the  weight  of  Fe2O3  in  i  gramme  of 
the  solution  of  ferric  chloride.  Take  the  mean  of  the  three  results 
obtained  in  this  way,  and  call  this  result  the  value  of  the  ferric 
chloride  solution  in  Fe2O3,  or  multiply  by  .7  for  its  value  in  Fe. 

To  standardize  the  permanganate  or  bichromate  solution, 
weigh  out  three  portions  of  the  ferric  chloride  solution  into  the 
flasks,  reduce  them  by  the  method  selected,  and  titrate  the  re- 
duced solutions  exactly  as  directed  above.  Before  calculating  the 
strength  of  the  standard  solution  a  small  correction  must  be  ap- 
plied to  the  burette  reading,  due  to  the  fact  that  a  definite  amount 
of  oxidizing  solution  is  required  to  produce  the  end  reaction  in  all 
cases  where  permanganate  is  used,  and,  when  bichromate  is  used, 
in  those  cases  where  zinc  has  been  the  deoxidizing  agent. 

Treat  3  grammes  of  zinc  in  a  small  flask  with  5  c.c.  HC1  and   Determina- 
20  c.c.  H2O,  add  gradually  10  c.c.  H2SO4  and  20  c.c.  H2O.     When     thecor- 
the  zinc  has  all  dissolved,  place  the  flask  in  cold  water  until  the     ^  zinc, 
solution  is  cold.     Wash  it  out  into  the  dish,  dilute  to  I  litre,  add 
20  c.c.  ferric  chloride  solution  (free  from  ferrous  salt),  and  drop  in 
the  standard  solution  until  the  end  reaction  is  obtained.     Subtract 
the    correction   thus    obtained   from    every   burette   reading.     To 
calculate  the  strength  of  the  standard  solution,  therefore,  subtract 


I §2  THE    CHEMICAL   ANALYSIS  OF  IRON. 

the  correction  from  the  burette  reading,  and  the  result  is  the  abso- 
lute  volume    of   the   standard    solution    required   to    oxidize   the 
ferrous    salt    in    the   solution    operated    on.      Knowing   then    the 
weight  of  the  ferric  chloride  solution  used,  the  amount  of  Fe  in 
each   gramme  of  the   solution,  and  the  volume  of  the  standard 
Calculation     required  to   oxidize  this  amount,   the  value   of  each   c.c.   of  the 
value         standard   solution   is   found  by  multiplying  the   weight  of   ferric 
standard     chloride  solution  used  by  the  value  of  each  gramme  in  Fe,  and 
lon-      dividing  the  amount  by  the  number  of  c.c.  of  the  standard  used 
in  titrating.     The  mean  of  the  results  obtained  in  the  three  por- 
tions used  should  be  taken  as  the  value  of  the  standard  solution. 
An  example  will    illustrate  the  method   of  computation,  and,  as 
logarithms  very  much    facilitate  these  calculations,  they  will   be 
given  in  the  example  as  well. 

Example  of     Weight  of  empty  flask 22.8817 

ca  cu  a-        Weight  of  flask  4-  ferric  chloride  solution  .  ,    40.0640 

tion. 

Weight  of  ferric  chloride  solution  used 17.1823  =  log.  1.2350813 

Value  of  ferric   chloride  solution,  determined  as  on 

p.  180 I  gramme  =  .03227  gramme  Fe^log.  8.5087990 — 10 

Fe  in  ferric  chloride  solution  used 5 5448  gramme  =  log.  9.7438803 — 10 

Burette  reading  after  titration —  82.0    c.c. 

Less  correction 0.25 

Corrected  reading 81.75  c.c.  •==  log.  1.9124878 


i  c.c.  standard  solution — .0067826  gramme  Fe  =:l°g-  7-8313925 — 10 

Calculation  Of  course  in  calculating  the  amount  of  Fe  in  an  ore  it  is  only 

of  Fe  in 

an  ore.  necessary  to  get  the  logarithm  of  the  corrected  reading  (page  176) 
and  add  it  to  the  logarithm  of  the  standard  solution  as  found 
above,  the  number  corresponding  to  the  resulting  logarithm  being 
the  weight  of  Fe  in  grammes  in  the  ore.  This  multiplied  by  100 
will  give  the  percentage. 
Use  of  iron  Very  fine  iron  wire  may  be  used  to  standardize  the  solutions, 

wire  for 

standard-  instead  of  a  standard  solution  of  ferric  chloride.  Weigh  into  the 
reducing  flasks  from  .4  to  .6  gramme  of  fine  iron  wire  (page  48) 
which  has  been  carefully  rubbed  with  fine  sand-paper  and  wiped 


ANALYSIS  OF  IRON  ORES.  jg. 

clean  with  a  linen  rag.  Dissolve  in  10  c.c.  HC1  and  20  c.c.  H2O, 
with  the  addition  of  a  few  small  crystals  of  KC1O3.  Deoxidize 
carefully,  and  titrate  as  before  directed.  Multiply  the  weight  of 
iron  wire  by  .998  to  get  the  absolute  amount  of  Fe  used,  apply 
the  proper  correction  to  the  burette  reading,  and  calculate  the 
value  of  the  standard. 

Ferrous  sulphate,  FeSO4,7H2O,*  containing  20.1439  per  cent.  Useoffer- 
Fe,  or  the  double  sulphate  of  iron  and  ammonium,  FeSO4,(NH4)2 
SO4,6H2O,*  containing  14.2857  per  cent.,  or  almost  exactly  -f  of 
its  weight  of  Fe,  may  be  used  instead  of  ferric  chloride  solution  or  sulPhate- 
iron  wire  to  determine  the  value  of  the  standard  solutions.  The 
pure  salts  are  generally  weighed  off,  dissolved  in  water  with  10  c.c. 
H2SO4,  added  and  titrated  direct,  but  they  are  not  so  satisfactory 
in  use  as  the  first  and  second  methods  described.  It  is  important  Degree  of 
to  have  the  standard  solutions  of  the  proper  strength;  that  is, 
neither  too  dilute  nor  too  concentrated  for  convenience  in  work- 
ing.  As  iron  ores  rarely  contain  more  than  60  per  cent,  metallic 
iron,  a  standard  solution  100  c.c.  of  which  are  equal  to  .66 
gramme  Fe  will  be  found  sufficiently  concentrated  to  avoid  the 
necessity  of  refilling  the  burette  for  a  determination ;  and  where 
ores  much  poorer  -than  this  are  habitually  used  the  solutions  may 
be  correspondingly  more  dilute. 

When  permanganate  of  potassium  is  added  to  a  solution  of 
ferrous  sulphate  the  reaction  is  ioFeSO4-f-  2KMnO4+8H2SO4  = 
5Fe2(SO4)3+K2SO4+2MnSO4+8H2O,  or  316.2  parts  by  weight 
of  KMnO4  will  oxidize  560  parts  by  weight  of  Fe,  or  3.727 
grammes  KMnO4  to  the  litre  will  give  a  solution  of  about  the 
strength  required. 

In  the  case  of  bichromate  of  potassium  the  reaction  is  6FeSO4 
+  K2Cr207+  7H2S04=3Fe2(S04)3  +  K2SO4+  Cr2(SO4)3+  /HA  or 
294.4  parts  by  weight  of  K2Cr2O7  will  oxidize  366  parts  of  Fe, 
or  5-783  grammes  of  bichromate  of  potassium  dissolved  in  I 

*  See  page  48. 


1 84 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Preparation 
ervationo 


Best  form  of 


litre    of  water   will    give   a   solution    100   c.c.    of   which    will   be 
equivalent  to  about  .66  gramme  Fe. 

To  prepare  the  solutions,  therefore,  dissolve  the  above  weights, 
or  multiples  of  them,  in  pure  distilled  water,  allow  the  solution 
to  stand  for  some  little  time,  filter  through  asbestos,  and  dilute  to 
the  proper  volume.  Mix  thoroughly  by  shaking  in  the  bottle, 
and  standardize  as  above  directed.  The  solutions  should  be  kept 
in  glass-stoppered  bottles  in  a  dark  closet,  and  the  bottles  should 
be  well  shaken  whenever  the  solution  is  used. 

The  selection  of  a  burette  is  a  matter  of  importance.  The 
ordinary  Mohr  burette,  with  glass  tip  and  rubber  connection, 
cannot  well  be  used  with  permanganate,  and  stopcocks  of  glass 
are  liable  to  stick  and  break  or  leak.  The  most  satisfactory 
form  for  general  use  is  shown  in  Fig.  81. 

The  burette  is  attached  to  the  wooden  stand  by  bands  of 
German  silver  or  of  nickel.  The  top  of  the  burette  is  closed 
by  a  rubber  stopper  carrying  a  glass  tube  of  small  bore  con- 
nected by  rubber  tubing  with  a  small  glass  tube  attached  to  the 
back  of  the  burette-stand.  To  the  end  of  this  tube,  near  .the 
base  of  the  burette-stand,  is  attached  a  short  piece  of  heavy- 
walled  gum  tubing,  a,  passing  under  a  compressor  fixed  to  the 
base  of  the  stand.  Fig.  80  shows  the 
form  and  construction  of  the  clamp  or 
compressor.  By  applying  suction  at  the 
end  of  the  tube  b  the  standard  solution 
may  be  drawn  up  into  the  burette  a  little 
above  the  zero-mark,  and  the  compressor 
closed  down  on  the  tube  a,  holding  the 
liquid  in  the  burette  until  the  admission 
of  air  through  the  tube  a  allows  the  liquid 

to   flow  out  of  the   burette.     The   entire  practical   value  of  this 
burette*    depends    on   placing   a    drop   or   two    of  water   in    the 


FIG.  80. 


*  The  suggestion  of  Mr.  Thos.  H.  Garrett,  of  Philadelphia.  ' 


ANAL  YSIS  OF  IRON  ORES. 
FIG.  81. 


185 


THE    CHEMICAL   ANALYSIS   OF  IRON. 

tube  #,  which,  flowing  to  the  point  of  compression,  not  only 
closes  the  tube  hermetically  when  the  clamp  is  screwed  down, 
but  makes  it  possible,  by  a  slight  movement  of  the  clamp,  to 
admit  the  smallest  quantity  of  air  to  the  burette,  and  thus  to 
permit  the  liquid  to  flow  from  the  burette  at  any  desired  rate. 
The  flow  is  thus  controlled  by  the  left  hand  while  the  solution 
in  the  dish  is  stirred  with  the  right.  Towards  the  end  of  the 
operation  a  single  drop  may  be  made  to  flow  from  the  burette, 
when  the  clamp  is  closed  (not  too  tightly),  by  compressing  the 
tube  a  at  the  point  c  with  the  thumb,  and  forcing  a  little  air 
into  the  burette.  Even  a  fraction  of  a  drop  may  be  obtained 
by  touching  the  point  of  the  burette  with  the  stirring-rod.  The 
scale  shown  in  the  sketch  is  fixed  on  the  wall,  so  that  the  eye 
may  always  be  kept  at  the  proper  level  in  taking  the  readings 
of  the  burette. 


DETERMINATION    OF   IRON    EXISTING    AS    FeO. 

Many  iron  ores  contain  iron  in  the  state  of  FeO,  and  this 
Feo  soluble  FeO  may  be  either  soluble  or  insoluble  in  HC1.  To  determine 
the  FeO  soluble  in  HC1,  weigh  I  gramme  of  the  finely-ground 
ore  into  the  flask  A,  Fig.  82,  of  about  100  c.c.  capacity.  Close 
the  flask  with  a  rubber  stopper  fitted  with  the  two  glass  tubes  B 
and  C,  and  place  it  in  the  position  shown  in  the  sketch.  Connect 
the  tube  C  by  means  of  a  piece  of  rubber  tubing  with  the  bent 
tube  D  dipping  below  the  surface  of  the  water  in  the  beaker  E. 
Pass  a  current  of  CO2  through  the  tube  B  until  all  the  air  is 
expelled,  then  remove  for  a  moment  the  rubber  tube  connecting 
B  with  the  source  of  CO2,  and  by  means  of  a  small  funnel  and 
rubber  connector  introduce  into  the  flask  A,  through  B,  10-12 
c.c.  strong  HC1,  and  establish  the  current  of  CO2  as  before.  Heat 
the  flask  carefully,  and  when  the  ore  is  entirely  decomposed,  or 
the  HC1  ceases  to  exert  any  further  action  on  it,  remove  the  source 


ANALYSIS  OF  IRON   ORES. 

of  heat,  stop  the  current  of  CO2  for  a  moment,  cool  the  flask  with 
the  hand,  and  allow  the  partial  vacuum  thus  formed  to  draw  the 
water  from  E  back  into  A.  Turn  on  the  current  of  CO2  again, 
place  a  dish  of  cold  water  under  the  flask  A,  and  allow  the  solu- 
tion to  cool.  Dissolve  in  a  small  flask  3  grammes  of  metallic 


FIG.  82. 


Q 


zinc  in  10  or  15  c.c.  H2SO4,  diluted  with  the  proper  quantity  of 
water,  cool  it,  and  have  it  ready  to  pour  into  the  titrating-dish 
by  the  time  the  solution  in  the  flask  A  is  cool.  Wash  out  the 
solution  of  the  ore  from  the  flask  A  into  the  dish,  add  the  zinc 
solution,  .dilute  to  I  litre,  and  titrate  with  a  standard  solution. 


i88 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Subtract  from  the  burette  reading  the  proper  correction,  calculate 
the  percentage  of  Fe,  divide  by  7,  and  multiply  by  9.    The  result  is 

Determina- 


tion of 
FeOin 
residue 
insoluble 
in  HC1. 


the  percentage  of  FeO  in  the  ore  soluble  in  HCL  Allow  the  solu- 
tion in  the  dish  to  stand  for  a  few  minutes,  when  all  the  undecom- 
posed  particles  of  ore  will  settle.  Draw  off  the  greater  part  of 

FIG.  83. 


NCHE8 


the  clear  supernatant  fluid  with  a  siphon,  wash  the  sediment  into 
a  beaker  with  a  jet  of  cold  water,  filter  on  a  thin  felt*  in  a  Gooch 
crucible,  and  wash  the  sediment  on  the  felt  with  cold  water. 
Transfer  the  felt  and  sediment  to  a  platinum  crucible,  pour  into 
the  crucible  5-10  c.c.  HC1  and  about  half  the  quantity  of  HF1, 


*  The  asbestos  of  which  the  felt  is  made  must  be  free  from  FeO. 


ANALYSIS  OF  IRON  ORES. 


189 


cover  the  crucible,  and  place  it  in  the  water-bath  shown  in  Fig. 
83.  The  crucible  rests  on  a  platinum  triangle  fixed  over  the  hole 
in  the  centre  of  the  tip  of  the  bath.  Around  this  hole  is  a  groove 
in  which  a  funnel  stands  as  shown  in  the  cut,  while  the  water  in 
the  groove  forms  a  tight  joint.*  Pass  a  current  of  CO2  or  coal- 
gas  through  the  tube  in  the  side  of  the  bath,  as  figured  in  the  cut, 
to  exclude  the  air,  and  heat  the  bath  until  the  residue  and  felt  are 
completely  dissolved.  Wash  the  crucible  out  into  the  titrating- 
dish,  into  which  have  been  poured  just  previously  3  grammes  of 
zinc  dissolved  in  H2SO4  and  enough  cold  water  to  make  the  solu- 
tion up  to  nearly  I  litre.  Titrate,  and  calculate  the  amount  of 
FeO  as  before. 

Of  course  separate  portions  of  the  ore  may  be  used  to  deter-  separate 
mine  the  FeO  soluble  and  insoluble  in  HC1,  but  it  is  more  trouble- 
some,  and  experience  has  shown  that  it  is  no  more  accurate,  and 
in  some  cases  less  accurate,  than  the  method  just  described. 

The  total  FeO  may  also  be  determined  in  one  operation  by  Total 
treating  i  gramme  of  the  ore  direct  in  the  crucible  with  20  c.c. 
HC1  and  20  c.c.  HF1,  but  it  is  often  difficult  to  get  the  ore  perfectly 
dissolved  even  by  prolonged  heating  in  the  bath,  and  the  ore  must 
be  ground  very  fine  in  the  agate  mortar.  It  is  necessary  to  re- 
move the  funnel  from  time  to  time,  raise  the  lid  of  the  crucible, 
and  stir  the  contents  with  a  platinum  wire. 

When  the  ore  is  completely  decomposed  by  HC1,  or  when 
the  portion  undecomposed  contains  no  FeO,  the  treatment  of  the 
residue  is  unnecessary. 

When  an  ore  contains  much  organic  matter,  an  accurate  deter- 
mination of  FeO  is  often  impossible,  as  the  solution  of  the  ore  in 
HC1  reduces  some  of  the  ferric  salt. 

*  Avery,  Chem.  News,  xix.  270 ;  Wilbur  and  Whittlesay,  Crook's  Select  Methods, 
page  133. 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


DETERMINATION    OF   SULPHUR. 

Sulphur  exists  in  two  conditions  in  iron  ores,  as  sulphur  in  the 
form  of  sulphides  and  as  sulphuric  acid  in  the  form  of  sulphates. 

Total  sui-  To  determine  the  total  sulphur,  weigh  I  gramme  of  the  finely- 
fusion.  ground  ore  into  a  large  platinum  crucible,  add  to  it  10  grammes 
of  Na2CO3  and  a  little  KNO3  (less  than  I  gramme).*  Mix 
thoroughly  with  a  platinum  wire,  and  heat  carefully  over  a  large 
Bunsen  burner  or  blast-lamp  until  the  mass  appears  perfectly 
liquid  and  in  a  tranquil  state  of  fusion.  Run  the  fusion  well  up 
on  the  sides  of  the  crucible,  allow  it  to  cool,  and  treat  it  in  the 
crucible  with  boiling  water.  Pour  the  liquid  into  a  tall,  narrow 
beaker,  treat  the  crucible  again  with  boiling  water,  and  repeat  the 
operation  until  all  the  sodium  salts  are  dissolved  and  nothing 
remains  in  the  crucible  except  the  unavoidable  stains.  Stir  the 
liquid  in  the  beaker  well,  and  allow  the  oxide  of  iron  to  settle.  If 

Evidence  of    the  solution  is  colored  red  or  green,  it  is  proof  of  the  presence  of 

manga- 

neseand     manganese  in  the  ore;  add  a  few  drops   of  alcohol,  which  will 

chromium. 

precipitate  the  manganese  as  oxide,  leaving  the  solution  colorless 
unless  the  ore  contains  chromium,  in  which  case  the  solution  will 
be  yellowish.  Decant  the  supernatant  liquid  on  a  small  filter, 
allowing  the  filtrate  to  run  into  a  No.  4  beaker,  fill  the  small  beaker 
nearly  full  of  hot  water,  stir  well,  and  allow  to  settle.  Decant  again 
on  the  filter,  and  repeat  the  operation  once  more.  Acidulate  the 
collected  filtrates  with  HC1  (about  20  c.c.  will  be  required),  evapo- 
rate to  dryness  in  the  air-bath,  redissolve  in  water  with  a  few  drops 
of  HC1,  filter  into  a  No.  3  beaker,  heat  the  filtrate  to  boiling,  and 
add  10  c.c.  of  a  solution  of  chloride  of  barium.f  Allow  to  stand 
for  some  hours,  filter  on  the  Gooch  crucible  or  on  a  small  ashless 
filter,  ignite,  and  weigh  as  BaSO4,  which  multiplied  by  .13/3  gives 
the  weight  of  S.  The  insoluble  portion  from  the  aqueous  solu- 

*  See  page  41.    It  is  well  to  make  a  blank  determination,  using  the  same  amounts 
of  Na2CO3,  KNO3,  and  HC1,  applying  the  amount  of  BaSO4  found  as  a  correction. 
f  See  page  44. 


ANALYSIS   OF  IRON  ORES. 

tion  of  the  fusion  may  be  used  to  determine  the  total  iron  in  the 
ore,  and  is  very  convenient  for  this  purpose  in  ores  difficult  to 
dissolve.  Pour  into  the  crucible  in  which  the  fusion  was  made 
about  10  c.c.  HC1,  place  the  lid  on  the  crucible,  and  warm  the 
crucible  slightly  to  dissolve  the  adhering  oxides,  dilute  with 
about  an  equal  bulk  of  water,  and  pour  it  on  the  small  filter 
through  which  the  aqueous  solution  was  decanted,  allowing  it  to 
run  into  the  beaker  which  contains  the  residue  of  oxide  of  iron, 
etc.  Wash  out  the  crucible,  pouring  the  washings  on  the  filter, 
and  wash  the  filter  free  from  iron  with  a  jet  of  cold  water.  Evap- 
orate the  solution  in  the  beaker  to  dryness,  redissolve  in  10  c.c. 
HC1,  and  transfer  the  solution  of  ferric  chloride,  the  silica,  etc., 
to  one  of  the  small  flasks,  deoxidize,  and  titrate  as  directed. 

The  sulphur  which  exists  as  sulphuric  acid  in  an  iron  ore 
is  usually  combined  with  either  calcium  or  barium  :  as  sulphate 
of  calcium  or  of  any  of  the  other  alkaline  earths  except  barium, 
of  the  alkalies,  or  of  the  metals,  it  is  soluble  in  HC1  ;  as  sulphate 
of  barium  it  is  practically  insoluble.  We  may,  therefore,  deter- 
mine the  soluble  sulphates  as  follows:  Boil  10  grammes  of  the 
ore  with  30  c.c.  HC1  and  60  c.c.  water,  filter  from  the  mass  of 
the  undissolved  ore,  evaporate  the  filtrate  to  dryness,  redissolve 
in  HC1  and  water  (1-2),  filter  into  a  No.  2  beaker,  nearly  neu- 
tralize by  NH4HO,  heat  to  boiling,  and  precipitate  by  BaCl2 
solution.  Filter  and  wash  the  precipitate,  ignite,  and  weigh  as 
BaSO4,  which  contains  34.335  per  cent.  SO3. 

To  determine  the  sulphuric  acid  which  exists  as  sulphate  of 
barium,  treat  10  grammes  of  the  ore  with  50  c.c.  HC1  until  the 
ore  appears  to  be  decomposed.  Evaporate  to  dryness,  redis- 
solve in  dilute  HC1  (1-3),  dilute,  filter,  and  wash  the  insoluble 
matter  thoroughly.  Ignite  and  fuse  the  insoluble  matter  with 
Na2CO3,  treat  the  fused  mass  with  hot  water,  and  filter.  In 
the  filtrate  is  the  sulphuric  acid  as  sulphate  of  sodium,  while 
the  barium  remains  on  the  filter  as  carbonate  of  barium.  It  is 
safer  to  calculate  the  sulphate  of  barium  from  the  amount  of 


lgl 


fosion- 


soluble 


sulphate 


S  as  sul- 
phides. 


THE    CHEMICAL   ANALYSIS   OF  IRON. 

barium  rather  than  from  the  amount  of  sulphuric  acid,  as  the 
ore  may  contain  sulphides  (pyrites,  etc.),  which  are  not  decom- 
posed by  HC1,  but  are  decomposed  and  partly  oxidized  by  fusion 
with  Na2CO3.  The  other  forms  of  barium  besides  the  sulphate 
(silicate  and  carbonate)  are  readily  decomposed  by  HC1,  and 
are  not  likely  to  be  found  with  the  barium  in  the  insoluble 
residue.  It  is,  of  course,  possible  to  suppose  the  coexistence 
of  silicate  or  carbonate  of  barium  and  of  sulphate  of  calcium 
in  an  ore,  and  the  consequent  formation  of  sulphate  of  barium 
when  the  ore  is  decomposed  by  HC1 ;  but,  as  the  soluble  sul- 
phuric acid  is  determined  in  one  operation  and  the  insoluble 
in  another,*  the  total  amount  of  sulphuric  acid  existing  as  such 
is  determined,  and  the  object  of  the  analysis  attained.  To  deter- 
mine the  barium,  then,  treat  the  insoluble  matter  obtained  by 
the  filtration  of  the  aqueous  solution  of  the  fusion  by  dilute 
HC1,  evaporate  to  dryness  to,  render  SiO2  insoluble,  redissolve 
in  water  with  a  few  drops  of  HC1,  filter  into  a  No.  2  beaker, 
heat  the  filtrate  to  boiling,  and  add  a  few  drops  of  H2SO4 
diluted  with  a  little  water.  Allow  the  precipitate  to  settle,  filter, 
wash,  ignite,  and  weigh  as  BaSO4,  from  which  weight  calculate 
the  amount  of  SO3  in  the  ore  insoluble  in  HC1.  To  find  the 
amount  of  sulphur  existing  as  sulphides,  subtract  from  the  total 
S  the  amount  of  S  in  the  SO3  found  as  sulphates. 


Solution  of 
the  ore. 


DETERMINATION    OF    PHOSPHORIC   ACID. 

Treat  5  or  10  grammes  of  the  finely-ground  ore  in  30  or 
60  c.c.  HC1.  (With  low  phosphorus  ores  use  10  grammes;  with 
others,  5  grammes.)  When  the  ore  is  decomposed,  evaporate 


*  The  insoluble  matter  from  the  treatment  of  10  grammes  of  the  ore  with  HC1 
for  the  determination  of  soluble  sulphates,  page  191,  may  be  used  to  determine  the 
sulphate  of  barium. 


ANALYSIS  OF  IRON   ORES.  !93 

to  dryness,  redissolve  in  20  or  40  c.c.  HC1,  dilute,  filter,  and 
proceed  exactly  as  directed  in  the  determination  of  phosphorus 
in  iron  and  steel,  page  73  et  seq.  The  weight  of  the  Mg2P2O7 
multiplied  by  .63964  gives  the  weight  of  the  P2O5.  The  weight 
of  the  phospho-molybdate  of  ammonium  multiplied  by  .0373  gives 
the  weight  of  the  P2O5. 

Titanic    acid    is   very   generally   found    associated   with   iron   Precautions 

.  -       .,  whenTiO. 

ores,   and   may   be    regarded   as    one  of  the   usual   constituents.     is  present. 
As  mentioned  on  page  77,  its  presence,  if  overlooked,  may  lead 
to  serious  errors  in  the  determination  of  phosphoric  acid.     When 
an  ore  contains    much  titanic   acid  it  may  readily  be  recognized   Means  of 
by   the   peculiar   milky   appearance   of  the    solution   when   it   is      [ng°tuan- 
diluted  preparatory  to  filtering  off  the   insoluble  matter,  and  by     jjj^ 
the  strong  tendency  it  shows  to  run  through  the  filter   as   soon 
as  the  attempt  is  made  to  wash  the  insoluble  matter  with  water. 
Smaller    quantities    of    titanic    acid    may   be    recognized   by   the 
clouding  of  the  solution  when  it  is  deoxidized  by  bisulphite  of 

ammonium,  as  noted  on  page  80.     In   the  latter  case,  however,  Ores  con- 
taining 
this    clouding   may  be   caused   by  the  formation  of  sulphate  of     barium. 

barium  when  the  ore  contains  the  latter  element  in  the  form 
of  carbonate  or  silicate.  Silica  in  the  solution  may  also  cause 
a  cloud  under  those  circumstances  which  closely  resembles  that 
caused  by  titanic  acid,  while  sulphate  of  barium  may  readily 
be  distinguished  from  either  by  its  granular  appearance  and 
its  tendency  to  settle  to  the  bottom  of  the  beaker. 

The  insoluble  residue  from  the  solution  of  the  ore  in  HC1 
should,  therefore,  be  treated  to  recover  any  P2O5  which  may 
have  remained  insoluble  in  combination  with  TiO2.*  An  ad- 

*  When  HF1  is  not  available,  fuse  the  residue  with  Na^Og,  treat  the  fused 
mass  with  hot  water,  filter,  acidulate  the  filtrate  with  HC1,  evaporate  to  dryness  to 
render  SiO2  insoluble.  Redissolve  in  water  with  a  little  HC1,  filter,  and  add  the 
filtrate  to  the  main  solution,  or  add  a  little  Fe2Cl6,  and  make  a.  separate  acetate 
precipitation  in  this  portion,  adding  the  solution  to  the  solution  of  the  main  acetate 
precipitation. 


194 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Additional 
test  for 
titanic 
acid. 


Fusion  of 
the  acetate 
precipi- 
tate with 
Na2CO3, 


ditional  test  for  the  presence  of  titanic  acid,  and  one  that  rarely 
fails  even  with  very  small  amounts,  is  to  dissolve  the  insoluble 
matter  from  the  aqueous  solution  of  the  fusion  of  the  residue 
from  the  HF1  and  H2SO4  treatment  of  the  insoluble  residue 
from  the  ore,  in  dilute  HC1,  allowing  it  to  run  into  a  test-tube 
and  adding  metallic  zinc.  When  titanic  acid  is  present  the  solu- 
tion becomes  first  colorless,  and  then  pink  or  purple,  and  finally 
blue  from  the  formation  of  Ti2O3.  The  simplest  way  is  to  pro- 
ceed as  directed  on  pages  79  and  80  when  using  the  acetate 
method,  or  on  page  85  when  using  the  molybdate  method. 
These  methods  are  not  practicable,  however,  when  the  ore 
contains  a  very  large  amount  of  TiO2,  and  recourse  must  be 
had  to  the  method  described  on  page  77  ct  seq.,  involving  the 
fusion  of  the  acetate  precipitate  and  the  residue  from  the  treat- 
ment of  the  insoluble  matter  with  HF1  and  H2SO4,  with  Na2CO3 
and  a  little  NaNO3.  It  is  best  to  pursue  this  method  at  any 
rate  whenever  TiO2  is  also  to  be  determined,  as  the  same  por- 
tion can  be  used  for  the  estimation  of  both  TiO2  and  P2O5,  and 
the  aggregate  labor  involved  is  much  lessened. 


Difficulties 
in  the  pre- 
cipitation 
of  Ti02. 


DETERMINATION    OF   TITANIC   ACID. 

The  determination  of  titanic  acid  has  always  presented  many 
difficulties,  and  its  separation  from  a  large  amount  of  oxide  of 
iron  and  alumina  has  been  far  from  satisfactory,  besides  being 
most  tedious.  The  principal  sources  of  error  in  the  estimation 
of  titanic  acid  in  iron  ores  are  the  tendency  of  P2O5  to  prevent  the 
precipitation  of  TiO2  by  boiling,  when  its  sulphuric  acid  solution 
contains  P2O5  and  ferrous  sulphate,  and  the  liability  of  A12O3  to 
separate  out  with  the  TiO2  when  the  latter  is  precipitated  under 
the  circumstances  above  mentioned.  There  is  also  a  mechanical 
difficulty,  caused  by  the  adhesion  of  the  precipitated  TiO2  to  the 
bottom  and  sides  of  the  beaker,  from  which  it  can  sometimes  be 


ANALYSIS   OF  IRON  ORES.  JQIJ 

removed  only  by  boiling  with  a  strong  solution  of  caustic  potassa. 
The  admirable  series  of  experiments  carried  out  by  Dr.  Gooch* 
on  the  separation  of  aluminium  and  titanium  suggests  a  method 
which  renders  the  determination  of  TiO2  in  iron  ores  much  less 
troublesome,  while  adding  greatly  to  the  accuracy  of  the  results. 
In  carrying  out  the  details  of  the  method,  dissolve  5  or  10  Details 
grammes  of  the  ore  in  HC1,  and  proceed  exactly  as  in  the  deter-  method, 
mination  of  P2O5,  by  fusing  the  residue  from  the  treatment  of  the 
insoluble  matter  by  HF1  and  H2SO4  and  the  acetate  precipitate, 
with  Na2CO3  and  a  little  NaNO3,f  and  then  complete  the  operation 
exactly  as  described  in  the  determination  of  Ti  in  pig-iron. J 

The  essential  points  in  this  method  are — i.  Separation  of  the  principles 
TiO2  from  the  mass  of  Fe2O3  by  acetate  of  ammonium  in  the 
deoxidized  solution.  2.  Separation  from  all  the  P2O5  and  the 
greater  part  of  the  A12O3  by  fusion  with  NagCO^  by  which  means 
a  titanate  of  sodium  insoluble  in  water  is  formed,  and  at  the  same 
time  phosphate  and  aluminate  of  sodium  soluble  in  that  men- 
struum. 3.  Separation  from  the  last  traces  of  A12O3  from  the  iron, 
calcium,  etc.,  by  precipitating  the  TiO2  in  the  thoroughly  deoxi- 
dized solution  in  the  presence  of  a  large  excess  of  acetic  acid  and 
some  SO2,  the  sulphuric  acid  being  all  in  the  form  of  sulphate 
of  sodium.  The  addition  of  a  large  excess  of  acetate  of  sodium, 
by  which  this  latter  condition  is  effected,  converts  all  the  sulphates 
of  iron,  calcium,  etc.,  into  acetates,  and  precipitates  the  TiO2 
almost  instantaneously  as  a  hydrate,  which  is  flocculent,  settles 
quickly,  shows  no  tendency  to  run  through  the  filter,  and  is 
washed  with  the  greatest  ease.  It  sometimes  happens  that  a  little 
FeO  is  precipitated  with  the  TiO2,  and  the  latter,  after  ignition, 
appears  discolored;  in  this  case  fuse  with  a  little  Na^jCOg,  add 
H2SO4  to  the  cold  fused  mass,  dissolve,  and  repeat  the  precipita- 

*  Proceedings  Am.  Acad.  Arts  and  Sciences,  New  Series,  vol.  xii.  p.  435. 
f  See  page  77  et  seq.  J  See  page  152  et  seq. 


196 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


tion  with  acetate  of  sodium   in  the  presence  of  sulphurous  and 
acetic  acids  exactly  as   in  the  first  instance. 

A  number  of  experiments  covering  all  the  points  involved  in 
this  method  show  it  to  be  extremely  accurate  and  entirely  trust- 
worthy. 


Ford's 
method. 


The  acetate 
method. 


FeO  and 

organic 
matter  in 
the  ores. 


Ores  con- 
taining 
MnOo. 


DETERMINATION    OF    MANGANESE. 

When  manganese  alone  is  to  be  determined  in  an  ore,  any 
one  of  the  methods  described  under  the  determination  of  manga- 
nese in  iron  and  steel,  page  90  et  seq.,  may  be  used.  The  most 
convenient,  however,  is  Ford's  method  with  the  modifications 
necessary  in  the  analysis  of  pig-iron,  page  98.  The  only  change 
requisite  is  to  evaporate  the  solution  in  HC1  to  dryness  to  render 
silica  insoluble  before  filtering  off  the  insoluble  matter. 

In  using  the  acetate  method  it  is,  of  course,  necessary  that 
all  the  iron  should  be  in  the  form  of  Fe2Cl6,  and  also  that  there 
should  be  no  oxidizing  agent  in  the  solution.  Even  a  very  small 
amount  of  FeCl2  will  cause  the  formation  of  a  brick-dust  precipi- 
tate, which  cannot  be  kept  from  passing  the  filter  while  some  of 
the  iron  remains  dissolved  in  the  acetate  solution.  When,  there- 
fore, the  ore  contains  FeO,  it  should  be  oxidized  by  HNO3  or 
KC1O3,  and  the  excess  of  the  oxidizing  agent  removed  by  evapo- 
ration with  HC1. 

When  the  ore  contains  much 'organic  matter  it  should  be  fil- 
tered off  before  attempting  to  oxidize  the  ferrous  salt,  as  it  is  quite 
impossible  in  some  cases  to  destroy  the  organic  matter,  and  reso- 
lution of  the  evaporated  mass  in  HC1  causes  a  reduction  of  some 
of  the  ferric  salt. 

Many  manganiferous  iron  ores  contain  manganese  in  a  higher 
state  of  oxidation  than  the  protoxide,  and  the  determination  of  the 
excess  of  oxygen  is  often  necessary.  All  ores  of  this  character 
when  treated  with  HC1  evolve  chlorine  gas,  which  is  easily  recog- 
nized by  its  yellowish-green  color  and  peculiarly  irritating  odor. 


ANALYSIS   OF  IRON   ORES. 

The  reaction  by  which  chlorine  is  liberated  is  MnO2-j-4HCl  = 
MnCl2-h2H2O-h2Cl,  or  each  molecule  of  MnO2=87  corresponds 
to  2  molecules  of  Cl  =  7i.  This  reaction  is  the  basis  of  Bunsen's 
method  for  the  estimation  of  the  amount  of  the  MnO2  in  manga- 
nese ores,,  which  consists  in  driving  the  liberated  Cl  into  a  solution 
of  iodide  of  potassium,  and  determining  the  amount  of  iodine  set 
free,  by  starch  and  hyposulphite  solution.  When  the  method 
given  on  page  60  et  seq.  for  determining  sulphur  in  steel  is  in 
use,  the  solutions  employed  in  carrying  out  that  method  (with 

FIG.  84. 


197 


the  exception  of  the  iodine  in  iodide  of  potassium)  can  be  used 
in  this,  or  they  may  be  prepared  by  the  directions  there  given,  for 
use  in  this  method. 

Weigh  from  .5  gramme  to  I  gramme  of  the  finely-ground  ore 
into  the  flask  a,  Fig.  84,  pour  in  10  c.c.  strong  HC1,  connect  the 


method. 


198 


THE   CHEMICAL  ANALYSIS   OF  IRON. 


Example. 


Determina- 
tion by 
means  of 
ferrous 
sulphate. 


bent  tube  b  quickly  by  means  of  a  piece  of  gum  tubing,  and  heat 
the  flask  gently  at  first  and  finally  to  boiling  to  drive  all  the  Cl 
over  into  the  tube  c,  which  contains  a  strong  solution  of  pure 
iodide  of  potassium  free  from  iodate.  This  tube  is  placed  in  ice- 
water.  When  all  the  Cl  has  been  expelled  from  the  flask  a  and 
absorbed  in  c,  detach  the  latter,  wash  its  contents  into  a  large  dish, 
add  a  little  starch  solution,  and  run  in  the  hyposulphite  until  the 
blue  color  just  vanishes.  If,  as  in  the  example  given  on  page  62, 
I  c.c.  of  the  hyposulphite  solution  is  equal  to  .01267  gramme  of 
iodine,  and  one  equivalent  of  chlorine  =  3 5. 5  replaces  one  equiva- 
lent of  iodine=i26.85  in  the  iodide  of  potassium,  i  c.c.  of  the 
hyposulphite  solution  would  be  equal  to  (126.85  :  35.5  ::  .01267 : 
.003546)  .003546  gramme  of  chlorine;  and,  as  I  equivalent  of 
MnO2=87  is  equal  to  two  equivalents  of  chlorine  =  7 1 ,  i  c.c.  of 
the  hyposulphite  would  be  equal  to  (71  :  87  ::  .003546  :  .004345) 
.004345  grammes  MnO2. 

In  most  laboratories,  however,  it  is  generally  more  convenient 
to  determine  the  amount  of  MnO2  in  an  ore  by  determining  its  oxi- 
dizing power  on  a  solution  of  ferrous  salt.  The  reaction  is  2FeSO4 
+  MnO2+  2H2SO  =  Fe2(SO4)3  +  MnSO4+  2H2O,  or  2  equivalents 
of  Fe  =  1 1 2  are  equal  to  i  equivalent  of  MnO2  =  87.  Grind  in  an 
agate  or  Wedgwood  mortar  about  10  or  15  grammes  of  ferrous 
sulphate  or  ammonio-ferrous  sulphate,  and  weigh  out  two  portions, 
one  of  2  grammes  and  one  of  3  to  8  grammes,  according  to  the 
quality  of  the  manganese  ore.  One  gramme  of  pure  MnO2  would 
oxidize  1.2874  grammes  of  Fe,  equal  to  nearly  6.5  grammes  of 
ferrous  sulphate,  or  more  than  9  grammes  of  ammonio-ferrous 
sulphate.  Transfer  the  2-gramme  portion  to  the  dish,  add  a  large 
amount  of  water  and  about  5  c.c.  HC1,  and  pour  in  3  grammes  of 
zinc  dissolved  in  10  c.c.  H2SO4  diluted  with  enough  water  to  dis- 
solve the  sulphate  of  zinc  readily.  Titrate  with  the  standard  solu- 
tion of  permanganate  or  bichromate  of  potassium  in  the  usual  way, 
and  calculate  the  amount  of  iron  in  I  gramme  of  the  ferrous  salt 
used.  Weigh  into  the  flask  A,  Fig.  82,  page  187,  I  gramme  of  the 


•   ANALYSIS   OF  IRON  ORES. 

finely-ground  ore,  and  add  to  it  the  larger  portion  of  the  ferrous 
salt  previously  weighed  out.  Connect  the  flask  as  in  Fig.  82,  and 
pass  in  a  current  of  CO2  until  the  air  has  been  driven  out.  Now 
pour  into  the  flask  A,  by  means  of  a  small  funnel  attached  to  B, 
10  c.c.  H.C1  and  30  c.c.  water,  reconnect  the  CO2  apparatus,  and 
while  the  current  of  CO2  is  passing  dissolve  the  ore,  heating  the 
flask,  and  shaking  it  from  time  to  tirrje  as  necessary.  When  the 
ore  is  all  decomposed,  stop  the  current  of  CO2  for  a  moment, 
remove  the  light,  and  allow  the  water  in  E  to  flow  back  into  the 
flask  A.  Transfer  the  solution  to  the  dish,  add  3  grammes  zinc 
dissolved  in  H2SO4,  and  titrate  it  with  the  standard  solution. 
From  the  titration  of  the  ferrous  salt  calculate  the  amount  of  Fe 
in  the  amount  used  in  the  solution  of  the  ore,  and  subtract  from 
this  the  amount  found  by  this  last  titration ;  the  difference  is  the 
weight  of  Fe  oxidized  by  the  chlorine  liberated  from  the  MnO2  in 
the  ore.  Then,  as  112  parts  of  Fe  correspond  to  87  parts  of 
MnO2,  multiply  the  above  weight  of  iron  by  87  and  divide  by 
112,  and  the  result  is  the  weight  of  MnO2  in  the  ore. 

The  total  Mn  having  been  determined  by  one  of  the  methods  caicuia- 
previously  given,  subtract  from  it  the  amount  of  Mn  as  MnO2  MQO 
(found  by  multiplying  the  weight  of  MnO2  by  .63218),  and  cal- 
culate  the  difference  to  MnO  by  multiplying  by  1.2909. 


DETERMINATION    OF    SILICA,     ALUMINA,  *^ 

MAGNESIA,  OXIDE  OF    MANGANESE,  AND  BA- 
RYTA. 

Treatment  of  iron  ores  with  HC1  leaves  a  residue  which  only  Composi- 
tion of 
in  very  rare  instances  consists  of  silica  alone,  being  usually  sili-      residue 

.  •         i          •   i  insoluble 

cates  of   aluminium,   calcium,   and   magnesium,    mixed   with   an     in  Hci. 
excess  of  silica.     These  silicates  are  often  much  more  complicated, 
and  contain,  besides  the  substances  enumerated  above,  protoxide 
of  iron,  soda,  potassa,  and  oxide  of  manganese.     With  these  sili- 


2OO 


THE    CHEMICAL   ANAL  YSfS   OF  IRON. 


cates  are  occasionally  found  titanic  acid,  titaniferous  iron,  chrome 
iron  ore,  sulphate  of  barium,  and  ferrous  sulphide,  besides  organic 
matter,  and  sometimes  graphite.  As  this  residue  must  be  fused 
with  Na2CO3  in  order  to  decompose  it,  and  the  introduction  of 
sodium  salts  into  the  main  solution  is  not  desirable,  the  two  por- 
tions of  the  ore  (the  soluble  and  the  insoluble  in  HC1)  should  be 
analyzed  separately. 

Weigh  i  gramme  of  ore  into  a  No.  I  beaker,  add  15  c.c.  HC1, 
cover  with  a  watch-glass,  and  digest  at  a  gentle  heat  until  the  ore 
appears  to  be  quite  decomposed,  add  a  few  drops  of  HNO3,  heat 
until  the  action  has  ceased,  and  then  wash  off  the  cover  with  a 
fine  jet  of  water,  and  evaporate  to  dryness.  Redissolve  in  HC1, 
and  evaporate  to  dryness  a  second  time  to  render  all  the  silica 

Solution  of  insoluble.  Redissolve  in  10  c.c.  HC1  and  30  c.c.  water,  filter, 
transfer  all  the  residue  to  the  filter  (a  small  ashless  filter)  with  a 
fine  jet  of  cold  water,  using  a  "  policeman"  to  detach  any  ad- 
hering particles  from  the  beaker,  and  wash  the  filter  with  a  little 
HC1  and  plenty  of  cold  water.  Allow  the  filtrate  and  washings 
to  run  into  a  No.  5  beaker,  and  ignite  and  weigh  the  residue  as 
"Insoluble  Silicious  Matter?' 

Analysis  of  Add  to  the  insoluble  matter  in  the  crucible  about  ten  times  its 

ubie  sm-  weight  of  pure  dry  Na2CO3  and  fuse  it.  Run  the  fusion  well  up 
on  the  sides  of  the  crucible  and  treat  it  with  hot  water.  Wash  it 
out  into  a  platinum  dish,  dissolve  any  particles  adhering  to  the 
crucible  in  HC1,  and  add  this  to  the  solution  in  the  dish.  Acidu- 
late with  HC1,  evaporate  to  dryness,  moisten  with  HC1  and  water, 
evaporate  to  dryness  a  second  time  to  render  silica  insoluble,  then 
pour  into  the  dish  5  c.c.  HC1  and  15  c.c.  water,  and  stand  it  in  a 
warm  place  for  some  time.  Dilute  with  about  20  c.c.  water,  filter 
on  a  small  ashless  filter,  wash  well  with  hot  water,  receiving  the 
filtrate  and  washings  in  a  small  beaker,  dry,  ignite,  and  weigh. 
Treat  the  ignited  precipitate  with  HF1  and  a  drop  or  two  of 
H2SO4,  evaporate  to  dryness,  ignite,  and  weigh  again.  The  differ- 

Sio2.  ence  between  the  two  weights  is  SiO2.     If  the  difference  between 


ANALYSIS   OF  IRON  ORES.  2OI 

the  last  weight  and  the  weight  of  the  empty  crucible  is  more  than   Nature  of 
a  milligramme  or  two,  the  residue  must  be  examined  and  its  nature     from  HFI 
determined.     This  residue  may  consist  of  titanic  acid,  sulphate  of     ^at^m* 
barium,  alumina,  or  sulphate  of  sodium  (from  imperfect  washing 
of  the  silica).     If  it  is  titanic  acid  or  alumina,  the  weight  must  be 
added  to  the  weights  of  the  A12O3,  etc. 

Return  the  filtrate  from  the  SiO2  to  the  dish  in  which  it  was 
previously  contained,  heat  to  boiling,  add  a  few  drops  of  bromine- 
water  and  an  excess  of  NH4HO,  boil  until  it  smells  but  faintly  Auo,,etc. 
of    NH3,    filter    on    a    small    ashless    filter,   wash   well   with   hot 
water,    dry,   ignite,   and   weigh   as   A12O3,   etc.     Besides   alumina  Possible 
this   precipitate   may   contain    titanic   acid,    sesquioxide  of  chro-     uems'of 
mium,  sesquioxide  of  iron,  oxide  of  manganese,  and  phosphoric     *Mtate~ 
acid. 

Return  the  filtrate  from  this  precipitate  to  the  dish,  evaporate 
down  to  about  100  c.c.,  add  oxalate  of  ammonium  and  ammonia, 
boil  for  a  few  minutes,  allow  the  precipitate  to  settle,  filter  on 
a  small  ashless  filter,  ignite  finally  for  five  minutes  over  a  blast- 
lamp,  and  weigh  as  CaO.  To  the  filtrate  from  the  oxalate  of  cao. 
calcium  add  microcosmic  salt  and  about  one-third  the  volume 
of  the  solution  of,  ammonia,  cool  in  ice-water,  stir  vigorously 
several  times,  and  allow  to  stand  overnight  so  that  the  precipi- 
tated Mg2(NH4)2P2O8  may  settle  properly,  filter,  wash  with  water 
containing  one-third  its  volume  of  ammonia  and  about  100 
grammes  of  nitrate  of  ammonium  to  the  litre,  ignite  carefully, 
and  weigh.  Dissolve  the  precipitate  in  the  crucible  in  a  little 
water  containing  from  5  to  10  drops  HC1,  filter  through  a  small 
ashless  filter,  which  dry,  ignite,  and  weigh.  The  difference  Mgo. 
between  the  two  weights  is  Mg2P2O7,  which,  multiplied  by 
.36036,  gives  the  weight  of  MgO. 

When  barium  has  been  shown  to  exist  in  the  ore,  as  noted  Analysis  of 

the  filtrate 

on  page  191,  heat  the  filtrate  from  the  Insoluble  Silicious  Matter  from  the 
to  boiling,  add  a  few  drops  of  H2SO4,  boil  for  a  few  minutes  snicious 
to  allow  the  precipitate  to  settle,  filter  on  a  small  ashless  filter, 

14 


momum. 


202  THE    CHEMICAL   ANAL  YSIS   OF  IRON. 

BaO.  allowing  the  filtrate  and  washings  to  run  into  a  No.  5  beaker, 

dry,  ignite,  and  weigh  as  BaSO4,  which,  multiplied  by  .65665, 
gives  the  weight  of  BaO. 

Predpita-  To  the  cold  filtrate  from  the  BaSO4  add  NH4HO  until  the  solu- 

aortate  ^on  *s  nearty  neutralized,  then  add  a  solution  of  carbonate  of  am- 
of  am-  monium  until  a  slight  permanent  precipitate  is  formed  which  fails 
to  dissolve  after  vigorous  stirring,  and  redissolve  this  by  the  care- 
ful addition  of  HC1,  drop  by  drop,  stirring  well,  and  allowing  the 
solution  to  stand  for  a  short  time  after  each  addition  of  HC1.  As 
soon  as  the  solution  clears,  add  a  solution  of  acetate  of  ammo- 
nium, made  by  slightly  acidulating  5  c.c.  of  NH4HO  by  acetic 
acid,  dilute  to  about  600  c.c.  with  boiling  water,  and  boil  for  a 
few  minutes.  Allow  the  precipitate  to  settle,  decant  the  clear 
liquid  through  a  large  washed  German  filter,  pour  the  precipitate 
on  the  filter,  and  wash  it  two  or  three  times  with  boiling  water. 
With  the  aid  of  a  platinum  spatula  return  the  precipitate  to  the 
beaker  in  which  the  precipitation  was  made,  dissolving  any  portion 
remaining  on  the  filter  or  adhering  to  the  spatula  in  dilute  HC1, 
allowing  the  acid  to  run  into  the  beaker  containing  the  precipitate. 
Wash  the  filter  thoroughly  with  cold  water,  and  evaporate  the 
solution  and  washings  to  dryness.  Redissolve  in  dilute  HC1, 
filter  into  a  large  platinum  dish,  dilute  with  hot  water,*  heat  to 
boiling,  and  add  a  slight  excess  of  ammonia.  Boil  for  a  few 
minutes  to  make  the  precipitate  granular  and  expel  the  excess  of 
ammonia,  and  filter  on  an  ashless  filter  (using  the  filter-pump 
and  cone,  page  21,  with  very  slight  pressure,  if  practicable).  Dis- 
solve any  of  the  adhering  particles  of  the  precipitate  in  the  dish 

*  The  distilled  water  used  in  the  complete  analysis  of  iron  ores  should  never  be 
heated  in  glass  vessels  for  any  length  of  time,  as  glass  is  sensibly  attacked  by  it.  An 
experiment  in  which  distilled  water  free  from  residue  was  heated  for  twelve  hours  in 
a  Bohemian  flask  showed  that  the  water  dissolved  52  milligrammes  of  solid  matter 
to  the  litre,  of  which  26  milligrammes  were  SiO2.  The  water  should  always  be  heated 
in  platinum  or  porcelain  dishes,  or  in  tin-lined  copper  flasks.  For  convenience,  the 
water  may  be  poured  into  the  washing-flasks  for  immediate  use. 


ANALYSIS   OF  IRON  ORES. 

in  a  very  few  drops  of  HC1,  heating  the  bottom  of  the  dish 
slightly,  wash  off  the  rod  and  cover,  and  wash  down  the  sides 
of  the  dish  with  hot  water,  add  a  slight  excess  of  ammonia,  heat 
gently  until  the  precipitate  of  ferric  hydrate  separates,  wash  this 
on  the  filter,  and  wash  the  precipitate  thoroughly  with  hot  water. 
Dry  the  filter  and  precipitate  carefully,  transfer  the  latter  to  a 
weighed  crucible,  burn  the  filter  in  a  wire,  add  the  ash  to  the 
precipitate,  and  heat  the  crucible,  keeping  it  carefully  covered,  and 
raising  the  heat  very  gradually  and  slowly  to  expel  the  last  traces 
of  moisture  from  the  precipitate  of  ferric  hydrate.  Finally  heat 
the  crucible  to  bright  redness,  and  then  to  the  highest  temperature 
of  the  blast-lamp  for  about  five  to  ten  minutes.  Cool,  ignite,  and  Fe  o  , 
weigh  as  Fe203  +  A12O3  +  P2O5(  +  TiO2  +  Cr2O3  +  As2O5). 

Add  the  filtrate  and  washings  from  the  acetate  precipitation  to 
those  from  the  precipitation  by  ammonia,  evaporate  down  to  about 
200  c.c.  in  a  platinum  dish,  filter  off  any  slight  precipitate  of  Fe2O3 
(which  must  be  ignited,  weighed,  and  the  weight  added  to  that  of 
the  Fe2O3,  etc.),  add  20  to  30  drops  of  acetic  acid,  heat  to  boil- 
ing, and  pass  a  current  of  H2S  through  the  solution  for  fifteen  or 
twenty  minutes,  keeping  the  solution  hot  during  the  passage  of 
the  gas.  Filter  off  the  precipitated  sulphides  of  copper,  zinc, 
nickel,  and  cobalt,  wash  with  H2S  water  containing  a  little  free 
acetic  acid,  and  to  the  filtrate  add  excess  of  ammonia  and  sul- 
phide of  ammonium.  Allow  the  precipitated  sulphide  of  man- 
ganese to  settle,  decant  the  clear,  supernatant  liquid  through  a 
filter,  but  before  pouring  the  precipitate  on  the  filter  remove  the 
beaker  containing  the  filtrate  and  substitute  a  clean  beaker,  for 
the  precipitate  is  almost  certain  at  first  to  run  through  the  filter. 
Wash  the  precipitate  and  filter  with  water  containing  a  little  sul- 
phide of  ammonium,  add  the  clear  filtrate  and  washings  together, 
and  stand  them  aside.  Dissolve  the  precipitate  of  sulphide  of 
manganese  on  the  filter  in  dilute  HC1,  and  wash  the  filter  thor- 
oughly with  hot  water,  receiving  the  solution  and  washings  in  a 
small  beaker.  Heat  to  boiling  to  expel  H2S,  and,  when  the  excess 


204 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


is  driven  off,  destroy  the  last  traces  with  a  little  bromine-water, 
transfer  the  solution  to  a  platinum  dish,  and  precipitate  by  micro- 
cosmic  salt  and  ammonia  as  directed  on  page  93.  Filter,  wash, 
ignite,  and  weigh  as  Mn2P2O7,  which,  multiplied  by  .5,  gives  the 
weight  of  MnO. 

Acidulate  the  filtrate  from  the  sulphide  of  manganese  with 
HC1,  boil  off  all  the  H2S,  filter  from  the  sulphur  deposited  by  this 
operation  into  a  platinum  dish,  add  an  excess  of  ammonia  and 
oxalate  of  ammonium,  filter  off,  ignite,  and  heat  at  the  highest 
temperature  of  the  blast-lamp  for  fifteen  minutes,  cool,  and  weigh 
Cao.  as  CaO. 

Precipitate  the  magnesia  in  the  filtrate  as  directed  on  page  201, 
and  determine  the  weight  of  Mg2P2O7,  which,  multiplied  by  .36036, 
MgO.  gives  the  weight  of  MgO. 

By  adding  the  elements  determined  in  the  insoluble  portion  to 
the  similar  ones  in  the  soluble  portion,  we  get  the  total  amounts 
of  each  in  the  ore.  Thus,  we  have  from  the  above  analysis 
SiO2,Fe2O3  +  A12O3  +  P2O5  +  Cr2O3  +  TiO2  +  As2O5,  MnO,  CaO, 
and  MgO,  and  it  becomes,  of  course,  necessary  to  calculate  prop- 
erly the  iron  in  its  different  states  of  oxidation  and  to  determine 
the  amount  of  A12O3  in  the  ore.  It  is  much  more  accurate  to 
determine  in  separate  portions  of  the  ore  the  amounts  of  P2O5, 
As2O5,  Cr2O3,  Fe2O3,  and  TiO2  than  to  attempt  to  make  the  sepa- 
ration in  the  precipitate  obtained  in  this  portion.  Therefore, 
knowing  the  amounts  of  these  substances,  the  Fe2O3  from  the  vol- 
umetric determination  of  iron,  as  previously  described,  and  the 
amount  of  each  of  the  others  as  found  by  one  of  the  methods 
given,  add  together  the  weights  of  the  Fe2O3,  the  P2O5,  the  Cr2O3, 
the  TiO2,  and  the  As2O5  in  one  gramme  of  the  ore,  and  subtract 
the  sum  from  the  weight  of  the  precipitate  obtained  in  the  above 
Ai2o8.  analysis,  the  result  is  the  weight  of  A12O3  in  one  gramme  of  the 
ore. 

Iron  may  exist  in  an  ore  in  several  conditions,  as  Fe2O3,  as 
FeO,  as  FeS2,  as  FeAs2,  etc.  While  it  may  not  always  be  possible 


ANALYSIS   OF  IRON  ORES. 

to  determine  the  exact  conditions  in  which  it  exists,  the  rule 
usually  followed  is,  after  subtracting  from  the  sulphur  existing 
as  sulphides  (page  192)  the  amount  necessary  to  form  sulphide 
of  copper,  sulphide  of  nickel,  etc.,  to  calculate  the  remainder  as 
FeS2  by  multiplying  the  weight  of  S  by  1.875.  The  weight  of  S 
subtracted  from  this  gives  the  weight  of  iron  in  the  FeS2.  Now 
from  the  weight  of  FeAs2  subtract  the  weight  of  arsenic,  and  the 
result  is  the  weight  of  iron  existing  as  Fe  in  the  FeAs2.*  Add 
the  Fe  in  the  FeS2  to  the  Fe  in  the  FeAs2,  and  subtract  this 
weight  from  the  Fe  found  as  FeO,  the  remainder  calculated  to 
FeO  is  the  amount  of  FeO  in  the  ore.  Subtract  the  total  amount  Feo. 
of  Fe  found  originally  by  titration  to  exist  as  FeO  from  the  total 
Fe  found  in  the  ore,  and  calculate  the  remainder  to  Fe2O3.  FejO,. 

When  an  iron  ore  contains  only  a  very  small  amount  of  man-  Method  for 
ganese,  the  acetate  separation  may  be  omitted  in  the  method  as 
given  above,  which  simplifies  and  shortens  the  operation  very 
materially.  In  this  event  transfer  the  filtrate  from  the  insoluble 
silicious  matter  at  once  to  a  large  platinum  dish,  heat  to  boiling, 
add  a  few  c.c.  of  bromine-water  and  then  excess  of  ammonia,  boil, 
and  filter  the  Fe2O3,  etc.,  on  an  ashless  filter,  dry,  ignite,  and 
weigh,  as  described  above.  The  manganese  will  be  in  the  pre- 
cipitate after  ignition  as  Mn3O4,  and  the  amount  calculated  from 
the  determination  of  manganese  made  in  a  separate  portion  of  the 
ore  must  be  subtracted  from  the  weight  of  the  above  precipitate 
in  calculating  the  amount  of  A12O3. 

The  lime  and  magnesia  are  determined  in  the  filtrate  from  the 
Fe2O3,  etc.,  providing,  of  course,  that  the  ore  contains  only  minute 
amounts  of  nickel,  copper,  etc. 

The  same  general  method  described  above  is  applicable  when 
the  ore  contains  quite  a  large  amount  of  titanic  acid,  so  much, 
in  fact,  as  to  cause  the  cloudiness  in  the  filtrate  from  the  insolu- 
ble silicious  matter,  as  noted  on  page  193.  Whenever  an  acetate 


*  All  the  weights,  of  course,  are  calculated  to  I  gramme  of  ore. 


2o6 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


separation  is  necessary  in  an  ore  of  this  character,  the  precipitate 
must  be  filtered  on  an  ashless  filter,  and  this  filter,  as  well  as  the 
filter  containing  any  insoluble  matter  from  the  resolution  of  the 
acetate  precipitate,  must  be  ignited  and  examined  for  TiO2  by 
treating  the  residue  with  HF1  and  H2SO4,  heating  to  redness, 
fusing  with  Na2CO3,  dissolving  in  HC1  and  water,  and  precipi- 
tating by  ammonia.  The  precipitate  so  obtained  is  to  be  filtered, 
ignited,  and  the  weight  added  to  that  of  the  Fe2O3,  etc.  Ilmenite 
even,  when  very  finely  ground  in  an  agate  mortar,  is  frequently 
capable  of  being  almost  entirely  decomposed  by  HC1,  and  when 
this  is  the  case  it  is  of  advantage  to  use  this  method  of  analysis. 
It  may  be  necessary,  however,  under  certain  circumstances  to 
decompose  the  ore  at  the  start  by  fusing  with  bisulphate  of  potas- 

Fusionwith  sium.  To  carry  out  this  method,  weigh  I  gramme  of  the  ore, 
which  has  been  ground  as  fine  as  possible  in  an  agate  mortar,  into 
a  large  platinum  crucible,  add  10  grammes  of  pure  bisulphate  of 
potassium,*  and  heat  the  crucible,  carefully  covered,  over  a  very 
low  light  until  the  bisulphate  is  melted.  It  is  necessary  to  watch 
this  operation  most  carefully,  for  the  bisulphate  has  a  strong 
tendency  to  boil  over,  and  only  unremitting  attention  on  the  part 
of  the  analyst  will  prevent  the  loss  of  the  analysis.  It  is  well  at 

Precautions  the  start  to  stand  by  the  crucible  and  raise  the  lid  slightly  at  very 
short  intervals  to  watch  the  condition  and  progress  of  the  fusion. 
The  lid  should  be  held  just  over  the  crucible  and  in  a  horizontal 
position,  otherwise  the  particles  which  have  spirted  on  it  from  the 
mass  in  the  crucible  may  run  to  the  edge  of  the  lid  and,  when  the 
latter  is  replaced,  down  the  outside  of  the  crucible.  Raise  the 
heat  very  gradually,  keeping  the  mass  just  liquid  and  the  tem- 
perature at  the  point  at  which  slight  fumes  of  SO3  are  given  off* 
when  the  lid  is  raised,  until  the  bottom  of  the  crucible  is  dull  red. 
When  the  ore  is  completely  decomposed,  remove  the  light,  take 
off  the  lid  of  the  crucible,  and  incline  the  latter  at  such  an  angle 


*  See  page  42. 


ANALYSIS   OF  IRON  ORES. 

that  the  fused  mass  may  run  together  on  one  side  of  the  crucible 
and  as  near  the  top  as  possible.  Allow  it  to  cool  in  this  position ; 
when  cold  it  is  easily  detached  from  the  crucible.  Place  the 
crucible  and  lid  in  a  No.  4  beaker  half  full  of  cold  water,  and  the 
fused  mass  in  the  little  basket,  as  shown  in  Fig.  69,  page  138. 
Pour  into  the  beaker  enough  strong  aqueous  solution  of  sulphur-  solution  of 
ous  acid  to  raise  the  liquid  to  the  top  of  the  basket,  and  allow  Lass"5* 
the  fusion  to  dissolve,  which  may  require  twelve  hours.  Wash  off 
with  a  jet  of  cold  water,  and  remove  the  basket,  the  crucible,  and 
lid,  stir  the  liquid,  which  should  smell  strongly  of  SO2,  and  allow 
the  insoluble  matter  to  settle.  Filter  on  an  ashless  filter,  wash 
well  with  cold  water,  dry,  ignite,  and  weigh.  Treat  with  HF1  and 
2  or  3  drops  of  H2SO4,  evaporate  to  dryness,  ignite,  and  weigh. 
The  difference  between  the  weights  is  SiO2.  If  any  appreciable  Sio2. 
residue  remains  in  the  crucible,  fuse  with  a  little  Na2CO3,  treat 
with  H2SO4,  and  add  to  the  main  filtrate.  To  the  main  filtrate, 
which  should  be  quite  colorless  and  which  should  smell  strongly 
of  SO2,  add  a  clear  filtered  solution  of  20  grammes  of  acetate  of 
sodium  and  one-sixth  of  its  volume  of  acetic  acid,  1.04  sp.  gr., 
heat  to  boiling,  and  boil  for  a  few  minutes.  Allow  to  settle,  filter 
on  an  ashless  filter,  wash  thoroughly  with  hot  water  containing 
one-sixth  its  volume  of  acetic  acid,  and  finally  with  hot  water,  dry, 
ignite,  and  weigh  as  TiO2.  This  precipitate,  however,  may  not  be  Treatment 

of  impure 

quite  pure,  as  small  amounts  of  ferric  oxide  and  alumina  may  be  precipitate 
carried  down  with  it.  The  best  plan  to  pursue  is  to  fuse  with 
Na2CO3,  dissolve  in  water,  filter,  wash,  dry,  and  fuse  the  insoluble 
titanate  of  sodium,  etc.,  with  Na2CO3,  treat  the  cooled  mass  in  the 
crucible  with  H2SO4,  and  precipitate  and  determine  the  TiO2  as  Tio2. 
directed  above.  The  two  filtrates  from  the  treatment  of  the  first 
precipitate  of  TiO2  may  contain  a  little  oxide  of  iron  and  alumina. 
To  recover  this,  boil  down  the  last  filtrate  until  the  greater  part  of 
the  sulphurous  acid  has  been  driven  off,  add  bromine-water  to  oxi- 
dize the  iron,  acidulate  the  aqueous  filtrate  from  the  carbonate  of 
sodium  fusion  with  H2SO4,  add  it  to  this  solution,  boil  the  united 


208 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


Fe2O3  and 
AUO3  car- 
ried down 
with  first 
precipitate 
of  Ti02. 


Fe203  + 

AloOg  + 
P205. 


Fe203. 
A1203. 


MnO,  CaO, 
MgO. 


solutions  down  in  a  platinum  dish  to  a  convenient  volume,  and  add 
a  slight  excess  of  ammonia.  Boil  the  solution  until  it  smells 
faintly  but  decidedly  of  ammonia,  filter  off,  and  wash  slightly. 
Redissolve  the  precipitate  in  HC1,  and  reprecipitate  by  ammonia, 
filter,  wash,  ignite,  and  weigh  as  Fe2O3  -f-  A12O3,  to  be  added  to  the 
main  precipitate.  Boil  the  main  filtrate  and  washings  down  in  a 
large  platinum  dish  after  adding  enough  bromine-water  to  oxidize 
all  the  iron,  add  HC1  from  time  to  time  when  necessary  to  keep 
the  iron  in  solution,  and,  when  reduced  to  a  convenient  bulk, 
nearly  neutralize  by  ammonia,  and  boil.  Filter  off  and  wash  the 
precipitate  two  or  three  times,  redissolve  and  reprecipitate  by 
ammonia,  filter,  wash,  dry,  ignite,  and  weigh  as  Fe2O3 -f-  A12O3  -f 
P2O5.  Fuse  this  precipitate  for  a  long  time  and  at  a  high  tempera- 
ture with  Na2CO3,  dissolve  in  water,  wash  by  decantation,  redis- 
solve the  insoluble  Fe2O3,  etc.,  in  HC1,  and  determine  the  iron  by 
titration.  Determine  the  alumina  by  difference,  the  P2O5  being 
determined  in  a  separate  portion.  In  the  filtrate  from  the  Fe2O3-f 
A12O3  -|-  P2O5  determine  manganese,  lime,  and  magnesia  in  the 
usual  way. 


DETERMINATION    OF    SILICA. 

When  silica  alone  is  wanted  in  an  ore  a  more  rapid  method  is 
sometimes  desirable.  In  this  case  dissolve  I  gramme  of  the  ore  in 
HC1,  evaporate  to  dryness,  redissolve  in  dilute  HC1,  filter  on  an 
ashless  filter,  wash,  dry,  ignite,  and  weigh  the  insoluble  silicious 
matter.  Treat  this  in  the  crucible  with  HF1  and  a  few  drops  of 
H2SO4,  evaporate  to  dryness,  ignite,  and  weigh.  It  is  evident  now 
Lossbyvoi-  that  if  the  insoluble  silicious  matter  contains  calcium,  magnesium, 

atilization 

with  HFI    potassium,  or  sodium,  the  loss  of  weight,  which  in  the  absence  of 

so4.          these  elements  would  represent  the  SiO2  volatilized  as  fluoride  of 

silicon,  will  be  decreased  by  the  amount  of  sulphuric  acid  which, 

uniting  with  these  elements,  remains  as  a  part  of  the  residue  in  the 


ANALYSIS   OF  IRON  ORES.  2OO 

crucible.  It  is  a  simple  operation,  however,  to  fuse  this  residue 
with  Na2CO3,  dissolve  in  water,  acidulate  with  HC1,  heat  to  boil- 
ing, add  solution  of  BaCl2  and  filter  off,  and  weigh  the  precipitated 
BaSO4.  This  being  accomplished,  calculate  the  amount  of  SO3, 
and  add  its  weight  to  the  loss  by  volatilization.  The  result  is  the 
weight  of  SiO2.  When  the  ore  contains  appreciable  amounts  of  sio2. 
sulphate  of  barium  this  method  is  not  admissible. 

Separation  of  Alumina  from  Ferric  Oxide. 

Besides  the  indirect  method  for  determining  alumina,  it  is 
sometimes  necessary  or  convenient  to  make  a  direct  separation. 
The  method  usually  taken,  the  iron  and  alumina  being  in  solution 
in  HC1,  is  as  follows :  Add  to  the  solution  about  five  times  the  Separation 

by  citric 

weight  of  the  oxides,  of  citric  acid  (tartaric  acid  may  be  used,  but,      add,  am- 


monia. 


as  it  is  liable  to  contain  alumina,  citric  acid  is  preferable)  and  andsu'i- 
excess  of  ammonia.  If  the  solution  remains  clear,  heat  to  boiling, 
and  add  a  fresh  solution  of  sulphide  of  ammonium  until  all  the  nium- 
iron  is  precipitated.  If  the  solution  does  not  remain  clear  on  the 
addition  of  ammonia,  acidulate  with  HC1,  add  more  citric  acid,  and 
then  excess  of  ammonia.  Allow  the  sulphide  of  iron  to  settle, 
decant  the  clear  liquid  through  a  washed  filter,  throw  the  precipi- 
tate on  the  filter,  and  wash  it  well  with  water  containing  sulphide 
of  ammonium,  changing  the  beaker  into  which  the  washings  run 
before  each  addition  of  wash-water,  and  keeping  the  funnel  well 
covered  with  a  watch-glass.  Unite  the  filtrate  and  washings,  acidu- 
late with  HC1,  boil  until  the  precipitated  sulphur  agglomerates, 
filter  into  a  platinum  dish,  and  evaporate  to  dryness.  Heat  care- 
fully until  the  chloride  of  ammonium  is  volatilized  and  there 
remains  in  the  dish  a  mass  of  carbonaceous  matter  from  the 
decomposition  of  the  citric  acid.  The  expulsion  of  the  last  traces  Danger  of 
of  water  from  the  chloride  of  ammonium  nearly  always  causes  loss  spirting. 
by  spirting,  but  the  difficulty  may  be  entirely  avoided  by  placing 
the  dish  in  one  of  the  holes  of  the  air-bath  overnight,  after  having 
lightly  coated  the  upper  edge  of  the  dish  with  paraffine  or  grease 


2iQ  THE   CHEMICAL   ANALYSIS   OF  IRON. 

to  prevent  the  chloride  of  ammonium  from  creeping  over  the  top. 
This  long  heating  expels  the  last  traces  of  water  without  the  least 
disturbance,  and  the  dish  may  be  at  once  placed  over  a  Bunsen 
burner,  and  the  mass  in  it  decomposed  without  fear  of  loss. 
Transfer  the  carbonaceous  matter  to  a  crucible,  wiping  out  the 
dish  carefully  with  filter-paper,  and  placing  these  in  the  crucible 
also.  Burn  off  the  carbon  in  the  crucible,  fuse  the  residue  with 
Na2CO3  -and  a  little  NaNO3,  treat  with  water,  transfer  to  a  platinum 
dish,  dissolve  any  adhering  particles  in  the  crucible  in  HC1,  add 
this  to  the  solution  in  the  dish,  with  enough  HC1  to  acidulate  it, 
heat  to  boiling  after  diluting,  add  a  slight  excess  of  ammonia,  boil 
until  the  solution  smells  but  faintly  of  NH3,  filter,  wash  thor- 

Ai2o3.  oughly,  ignite,  and  weigh  as  A12O3.  This  precipitate  will  contain 
any  P2O5,  Cr2O3,  and  TiO2  that  may  have  been  in  the  original  solu- 

impurities.  tion.  They  may  be  separated  by  the  methods  given  on  page  161 
et  seq.  It  is  liable  to  contain  also  a  little  iron,  which  is  almost 
invariably  held  in  solution  by  the  sulphide  of  ammonium. 

Dissolve  the  precipitate  of  ferrous  sulphide  on  the  filter  in 
dilute  hot  HC1,  allow  the  solution  and  washings  to  run  into  the 
beaker  in  which  the  precipitation  was  made,  add  a  little  HNO3, 
evaporate  to  dryness,  redissolve  in  as  little  dilute  HC1  as  possible, 
filter  into  a  platinum  dish,  dilute,  precipitate  by  ammonia,  filter, 

Fe2o3.          wash,  dry,  ignite,  and  weigh  as  Fe2O3. 

Separation  Rose  *  suggested  the  method  based  on  the  solubility  of  alu- 

potaswTor  mma  m  caustic  potassa  or  soda.  When  the  iron  and  alumina  are 
in  solution,  evaporate  until  syrupy  in  a  platinum  dish,  add  a  strong 
solution  of  caustic  soda  or  potassa  until  the  solution  is  strongly 
alkaline,  and  then  add  a  large  excess  of  the  precipitant,  and  boil 
for  ten  or  fifteen  minutes;  or,  pour  the  nearly  neutral  solution  of 
the  chlorides  into  a  boiling  solution  of  caustic  soda  or  potassa  in 
a  platinum  or  silver  dish,  in  a  thin  stream,  stirring  continually. 
Filter,  wash  with  hot  water,  carefully  acidulate  the  filtrate  with 

*  Chimie  Anal.  Quant.  (French  ed.),  page  148. 


ANALYSIS   OF  IRON  ORES.  2ll 

HC1,  and  precipitate  the  alumina  by  ammonia,  filter,  wash,  dis- 
solve in  HC1,  evaporate  to  dryness  to  get  rid  of  SiO2,  redissolve, 
filter,  and  determine  as  usual.  As  the  Fe2O3  precipitated  by  caus- 
tic soda  or  potassa  always  contains  alkali,  it  must  be  dissolved  in 
HC1,  precipitated  by  ammonia,  filtered,  and  weighed  in  the  usual 
manner. 

Rose  also  suggested  fusing  the  finely-ground  ignited  oxides 
in  a  silver  crucible  with  potassium  or  sodium   hydrate ;  but  this 
method,  as  well  as  the  other,  is  open  to  the  objection  that  it  is  Objection 
almost  impossible  to  get  caustic  soda  or  potassa  that  does  not  con-     method, 
tain  alumina,  and  generally  there  would  be  more  in  the  reagent 
than  in  the  ore. 

Rivot  suggested   the  following  method :    After  weighing  the  voiadiiza- 
ignited  oxides  of  iron  and  aluminium,  grind  them  very  fine,  and     current  of 
weigh  them  into  a  porcelain  or  platinum  boat.     Place  the  boat     afterre-S 
in  a  porcelain  or  platinum  tube,  and   heat  to  redness  in  a  cur-     ^FeV* 
rent  of  hydrogen  gas  until  no  more  H2O  appears  to  come  off.      H 
Replace  the  hydrogen  by  a  stream  of  HC1  gas,  reheat  the  tube, 
and  continue  the  current  as  long  as  ferric  chloride  is  given  off. 
Remove  the  boat,  and,  if  the  residue  is  not  white,  repeat  the  opera- 
tion.    Weigh  the  remaining  A12O3,  and  calculate  from  the  amount 
of  the  oxides  used  the  total  amount  in  the  ore. 

Rose  modified  this  method  by  substituting  a  crucible  and  tube  Rose's  mod- 

ification. 

for  the  boat,  etc.  The  apparatus  as  he  used  it  is  the  same  as 
that  described  for  the  determination  of  manganese  as  sulphide, 
page  94. 

Wohler  suggested  the  method  of  separating  iron  and  alumina  Separation 

by  hypo- 

by  boiling  the  nearly  neutral  solution  with  an  excess  of  hypo-     sulphite  of 

sodium. 

sulphite  of  sodium.  The  following  modification  of  this  method  * 
appears  to  give  excellent  results,  and  has  the  advantage  of  doing 
away  with  a  subsequent  separation  of  P2O5  in  those  cases  in  which 
it  has  not  been  determined  in  another  portion.  The  Fe2O3  and 

*  Communicated  to  me  by  Mr.  S.  Peters  in  1879. 


212 

Peters's 
modifica- 
tion. 


THE    CHEMICAL  ANALYSIS   OF  IRON. 

A12O3  from  I  gramme  of  ore  being  in  solution  in  HC1,  dilute  to 
400  or  500  c.c.  with  cold  water,  and  add  ammonia  until  the  solu- 
tion becomes  dark  red  in  color,  but  contains  no  precipitate.  Now 
add  3.3  c.c.  HC1,  1.2  sp.  gr.,  and  2  grammes  phosphate  of  sodium, 
dissolved  in  water  and  filtered ;  stir  until  the  precipitate  formed  is 
dissolved  and  the  solution  becomes  perfectly  clear  again.  Add 
now  10  grammes  of  hyposulphite  of  sodium,  dissolved  in  water 
and  filtered  if  necessary,  and  15  c.c.  of  acetic  acid,  1.04  sp.  gr., 
heat  to  boiling,  boil  fifteen  minutes,  filter  as  rapidly  as  possible  on 
an  ashless  filter,  wash  thoroughly  with  hot  water,  dry,  ignite  in  a 
porcelain  crucible,  and  weigh  as  A1PO4,  which,  multiplied  by  .4204, 
gives  the  weight  of  A12O3.  It  is  necessary  in  burning  off  the  pre- 
cipitate to  raise  the  heat  very  carefully  until  all  the  carbon  has 
been  burned  off,  as  the  A1PO4  may  fuse  and  make  it  almost 
impossible  to  burn  off  the  carbon. 


Solution  of 
the  ore. 


DETERMINATION    OF    NICKEL,    COBALT,    ZINC, 
AND    MANGANESE. 

For  the  determination  of  these  elements  use  3  grammes  of 
ore,  dissolve  in  HC1,  add  a  little  HNO3  or  KC1O3  to  oxidize  any 
FeO  in  the  ore,  evaporate  to  dryness,  redissolve  in  HC1,  and  evap- 
orate a  second  time  if  necessary  to  get  rid  of  all  HNO.  As  noted 
on  page  196,  when  the  ore  contains  much  organic  matter,  dissolve 
in  HC1  (if  there  is  much  gelatinous  silica,  evaporate  to  dryness  or 
the  filtration  will  be  much  retarded),  filter,  add  HNO3  or  KC1O3, 
evaporate  to  dryness,  redissolve  in  HC1,  and  evaporate  a  second 
time  if  necessary,  redissolve  in  10  c.c.  HCl  and  20  c.c.  water,  dilute, 
filter  into  a  No.  6  beaker,  and  proceed  exactly  as  directed  for  the 
determination  of  manganese  in  iron  and  steel,  page  90  et  seq., 
until  the  precipitate  by  H2S  is  obtained  and  filtered  off.  Deter- 


ANALYSIS   OF  IRON  ORES.  213 

mine  the  manganese,  if  desired,  in  the  filtrate,  as  directed  on  page 

92,  and  calculate  to  MnO.  Mno. 

Dry  and  ignite  the  precipitated  sulphides  of  nickel,  cobalt,  zinc, 
copper,  lead,  etc.,  in  a  porcelain  crucible,  transfer  to  a  small  beaker, 
and  dissolve  in  HC1,  with  the  addition  of  a  drop  or  two  of  HNO3. 
Evaporate  to  dryness,  redissolve  in  10  to  20  drops  HC1,  dilute  to 
50  or  60  c.c.,  heat  to  boiling,  and  pass  a  current  of  H2S  through 
the  boiling  solution.  Filter  off  the  precipitated  sulphides  of  cop-  sulphides 
per,  lead,  etc.,  and  wash  with  water  containing  H2S.  Evaporate  to 
dryness  the  filtrate,  which  contains  only  nickel,  cobalt,  and  zinc. 
To  the  dry  salts  in  the  bottom  of  the  beaker  add  2  drops  of  strong 
HC1,  dilute  to  150  c.c.  with  cold  water,  and  pass  H2S  through  the 
solution  until  it  is  thoroughly  saturated  with  the  gas.  If  a  white 
precipitate  forms,  it  is  sulphide  of  zinc.  Allow  to  stand  several 
hours,  filter,  wash  with  H2S  water  (the  sulphide  of  zinc  has  a 
tendency  to  pass  through  the  filter,  and  consequently  the  beaker 
into  which  the  filtrate  is  received  must  be  changed  before  the  pre- 
cipitate is  poured  on  the  filter),  dry,  and  ignite  the  precipitate. 
Heat  it  several  times  with  carbonate  of  ammonium  to  drive  off  any 
sulphuric  acid  that  may  have  been  formed  by  the  ignition,  cool, 
and  weigh  as  Zn(X  The  precipitate  is  greenish  white  while  hot  Z 
and  yellowish  white  when  cold.  If  it  should  carry  down  a  little 
cobalt  from  the  solution,  the  ignited  precipitate  of  ZnO  is  green 
when  cold.  Pass  H2S  through  the  filtrate  from  the  ZnS  again, 
and,  if  no  further  precipitate  appears,  add  a  few  drops  of  a  solution 
of  .5  gramme  of  acetate  of  sodium  in  10  c.c.  water.  If  this  occa- 
sions a  white  precipitate,  filter  it  off,  after  standing,  as  in  the  first 
instance;  but  if  the  precipitate  is  black  (as  it  is  almost  certain  to 
be  if  the  instructions  given"  above  are  strictly  followed),  add  the 
rest  of  the  acetate  of  sodium  solution,  heat  the  solution  to  boiling, 
while  the  passage  of  the  H2S  is  continued,  allow  the  precipitate  to 
settle,  filter  it  off,  ignite  it,  and  treat  it  as  directed  for  the  separation 
and  determination  of  nickel  and  cobalt,  page  157  et  seq. 


THE    CHEMICAL   ANALYSIS   OF  IRON. 

DETERMINATION  OF  COPPER,  LEAD,  ARSENIC, 
AND  ANTIMONY. 

Treat  10  grammes  of  the  very  finely  ground  ore  with  50  c.c. 
HC1,  add  a  little  KC1O3  from  time  to  time,  and  increase  the  heat 
gradually  until  the  ore  is  perfectly  decomposed.  Dilute,  filter  into 
a  No.  5  beaker,  deoxidize  with  bisulphite  of  ammonium,  as  directed 
on  page  73,  drive  off  the  excess  of  SO2,  and  pass  H2S  through  the 
solution  for  fifteen  or  twenty  minutes.  Allow  the  solution  to  stand 
for  some  hours  until  the  precipitate  has  settled  completely  and  the 
solution  smells  but  faintly  of  H2S.  Filter  on  a  thin  felt  on  the 
Gooch  crucible  or  small  cone,  wash  with  cold  water,  and  suck  dry. 
Transfer  the  felt  and  precipitate  to  a  small  beaker,  using  a  little 
asbestos  wad  in  the  forceps  to  wipe  off  any  adhering  precipitate 
from  the  large  beaker  and  the  crucible  or  cone,  and  digest  it  with  a 
Separation  few  c.c.  of  a  colorless  solution  of  sulphide  of  potassium.  Dilute  to 

of  As  and 

sbfrom  about  100  c.c.,  filter  on  another  felt,  and  wash  with  water  contain- 
by  K!S  mS  a  ^ttle  sulphide  of  potassium.  The  solution  contains  the  sul- 
phides of  arsenic  and  antimony  dissolved  in  sulphide  of  potassium, 
while  the  sulphides  of  copper  and  lead  remain  in  the  felt.  Return 
the  felt  with  the  precipitate  to  the  beaker  from  which  they  were 
filtered,  and  digest  with  HC1,  with  the  addition  of  HNO3,  until  all 
the  black  sulphides  are  dissolved,  dilute  with  a  little  hot  water,  and 
filter.  Evaporate  the  filtrate,  after  adding  a  few  drops  of  H2SO4, 
until  fumes  of  SO3  are  evolved,  allow  to  cool,  dilute  with  25  c.c. 
cold  water,  add  one-half  its  bulk  of  alcohol,  allow  to  settle,  filter 
the  precipitated  PbSO4  on  the  Gooch  crucible,  wash  with  alcohol 
and  water,  heat  carefully  over  a  low  light,  and  weigh.  Treat  the 
precipitate  in  the  felt  under  a  slight  pressure  with  a  strongly  am- 
moniacal  solution  of  citrate  of  ammonium,  to  dissolve  the  PbSO4, 
wash  with  hot  water,  and  weigh.  The  difference  between  the  two 
weights  is  PbSO4,  which  multiplied  by  .68317  gives  the  weight 
s,  of  Pb,  or  multiplied  by  .7888  gives  the  weight  of  PbS. 

Evaporate  the  filtrate  from  the    PbSO4   until   the   alcohol    is 


ANALYSIS   OF  IRON  ORES.  2I- 

driven  off  and  the  solution  reduced  to  a  convenient  bulk,  transfer 
to   a  platinum  crucible,  and  precipitate  the  copper  on  the  small 
platinum   cylinder  by  the  battery,  page    155.     The  weight  of  Cu  cuand 
multiplied  by   1.2532  gives  the  weight  of  Cu2S. 

Acidulate  the  filtrate  of  sulphide  of  potassium  containing  ar- 
senic and  antimony  in  solution  with  HC1,  and  allow  to  stand  in  a 
warm  place  until  all  the  H2S  has  been  driven  off  and  the  sulphides 
of  arsenic  and  antimony  mixed  with  the  excess  of  sulphur  have 
settled  completely.  Filter  on  a  thin  felt,  wash  with  warm  water, 
then  with  alcohol,  and  finally  with  bisulphide  of  carbon,  to  dis- 
solve the  excess  of  S.  Transfer  the  felt  and  precipitate  to  a  small 
beaker,  add  5  c.c.  HC1  and  a  few  crystals  of  KC1O3.  Digest  at  Solution  of 
a  low  temperature  for  some  time,  adding  occasionally  a  small  crys- 
tal  of  KC1O3,  finally  heat  a  little,  but  not  to  a  sufficiently  high 
degree  to  fuse  any  little  particles  of  separated  sulphur,  keeping  the  HCI  and 

KC1O3- 

liquid  always  full  of  the  products  of  decomposition  of  the  KC1O3. 
When  all  the  sulphides  of  arsenic  and  antimony  are  dissolved, 
dilute  with  about  20  c.c.  of  warm  water,  and  add  a  few  small 
crystals  of  tartaric  acid  to  keep  the  antimony  in  solution.  Filter 
from  the  asbestos,  using  as  little  wash-water  as  possible  in  order 
to  keep  down  the  volume  of  the  solution,  add  a  slight  excess  of 
ammonia  to  the  filtrate,  and  if  it  remains  clear  5  c.c.  of  magnesia 
mixture  and  one-third  the  volume  of  the  solution  of  NH4HO. 
Cool  in  ice-water,  and  stir  vigorously  from  time  to  time  to  pre-  Mg8(NH,), 
cipitate  the  Mg2(NH4)2As2O8  +  Aq. 

Allow  to  stand  overnight,  filter,  and  determine  the  arsenic 
as  directed  on  page  165.  If  the  acid  solution  above  mentioned 
becomes  cloudy  upon  the  addition  of  NH4HO,  acidulate  care- 
fully with  HCI,  and  add  a  little  more  tartaric  acid.  Then  proceed 
as  above  directed.  The  weight  of  As  calculated  from  the  amount 
of  Mg2As2O7,  multiplied  by  1.373,  giyes  tne  weight  of  FeAs2.  FeA 

Acidulate  the  filtrate  from  the  Mg2(NH4)2As2O84-  Aq,  which 
contains  none  of  the  washings,  with  HCI  so  that  the  solution  is 
just  acid  to  test-paper,  dilute  with  hot  water  to  about  250  c.c., 


2I6  THE   CHEMICAL   ANALYSIS   OF  IRON. 

and  pass  H2S  into  the  solution,  heating  it  gradually  to  boiling. 
Drive  off  the  excess  of  H2S  with  a  current  of  CO2,  filter  on  a  felt 
in  the  Gooch  crucible,  wash  with  water,  alcohol,  and  finally  with 
bisulphide  of  carbon  to  dissolve  any  free  sulphur,  dry  carefully, 
heat  to  a  temperature  slightly  above  100°  C.,  and  weigh  as  Sb2S3. 
For  the  very  small  amounts  of  antimony  that  are  found  in  iron 
sbgSgand  ores  this  method  is  sufficiently  exact.  The  weight  of  Sb2S3  mul- 
tiplied by  .71765  gives  the  weight  of  Sb. 


DETERMINATION    OF   THE    ALKALIES. 

As  a  rule,  the  alkalies  in  iron  ores  are  found  exclusively  in  the 
insoluble  silicious  matter,  and  when  the  sum  of  the  weights  of  the 
SiO2,  A12O3  etc.,  CaO,  and  MgO  in  the  insoluble  silicious  matter 
falls  much  below  the  weight  of  the  latter,  it  is  always  well  to  look 
for  alkalies. 

Dissolve  3  grammes  of  the  ore  in  HC1,  evaporate  to  dryness, 
redissolve  in  10  c.c.  HCl-f-2O  c.c.  water,  dilute,  and  filter  into  a 
Treatment  of  platinum  dish.  Ignite  the  insoluble  residue,  treat  it  in  the  crucible 
with  HF1  and  10  to  30  drops  H2SO4,  evaporate  down  until  copious 
fumes  of  SO3  are  given  off,  dissolve  in  water  with  a  little  HC1  if 
necessary,  transfer  to  a  small  platinum  dish,  dilute  to  100  c.c.,  heat 
to  boiling,  and  add  excess  of  ammonia.  Boil  for  a  few  minutes, 
and  filter  from  the  A12O3  etc.  into  another  platinum  dish.  Evapo- 
rate the  filtrate  to  dryness,  and  heat  until  the  chloride  and  sulphate 
of  ammonium  are  volatilized.  Treat  the  residue  with  a  little  water, 
heat  to  boiling,  and  add  enough  oxalate  of  ammonium  to  precipi- 
tate all  the  calcium,  filter  into  another  platinum  dish,  evaporate  to 
dryness,  and  heat  to  dull  redness.  Treat  the  residue  with  a  little 
water,  heat  the  filtrate  to  boiling,  add  enough  acetate  of  barium  to 
precipitate  all  the  H2SO4,  boil,  and  filter.  Evaporate  the  filtrate  to 
dryness  and  heat  to  redness  to  decompose  the  acetates.  Treat  the 


ANALYSIS  OF  IRON  ORES.  2I- 

residue  with  water,  filter  from  the  insoluble  carbonate  of  barium, 
add  a  few  drops  of  barium  hydrate,  and  evaporate  again  to  dry- 
ness.  Dissolve  in  a  few  c.c.  of  water,  and  filter  into  a  weighed 
crucible. 

Evaporate  very  low,  and,  if  nothing  separates  out,  add  a  few 
drops  of  HC1,  evaporate  to  dryness,  heat  to  very  dull  redness,  cool, 
and  weigh  as  KCl  +  NaCl.     To  the  residue  in  the  crucible  add  a  KCI  + 
little  water,  in  which  the  residue  should  dissolve  perfectly,  and  a 
solution  of  platinic  chloride.     Evaporate  down  in  the  water-bath 
until  the  mass  in  the  crucible  solidifies  upon  cooling,  add  a  little 
water  to  dissolve  the  excess  of  platinic  chloride,  and  then  an  equal 
volume  of  alcohol.     Filter  on  a  Gooch  crucible,  wash  with  alco- 
hol until  the  filtrate  runs  through  perfectly  colorless,  dry  at  120° 
C,  and  weigh  as  K2PtCl6.     This  weight  multiplied  by  .1931  gives  K2Ptcifl. 
the  weight  of    K2O.      Then  multiply  the  weight  of  K2PtCl6  by  K2o. 
.3056,  which  gives  the  weight  of  KC1.     Subtract  this  from  the  KG. 
weight  of  KC1  +  NaCl  previously  obtained,  and  the  difference  is  Nad. 
the  weight  of  NaCl,  which  multiplied  by  .5299  gives  the  weight  Na,,o. 
of  Na20. 

To  the  filtrate  from  the  insoluble  silicious  matter  add  an  excess 
of  ammonia,  rub  a  little  grease  or  parafrine  on  the  edge  of  the 
dish,  and  evaporate  the  mass  to  dryness.     This  will  render  the 
Fe2O3  very  compact  and  granular.     Dilute  with  hot  water,  add  a  Treatment 
few  drops   of  ammonia,  filter  into  another  platinum  dish,  add  a     tionofthe 
few  drops  of  H2SO4,  evaporate  to  dryness,  and  ignite  to  drive  off     in  Hci. 
all  the  ammonia  salts.     Then  proceed  exactly  as  directed  for  the 
determination  of  the   alkalies   in   the   insoluble   silicious   matter.  DecomP°si- 

tion  of  in- 

The  alkalies  in  the  insoluble  silicious  matter  may  also  be  deter-     soluble 

matter  by 

mined  by  J.  Lawrence  Smith's  method  of  fusion  with  carbonate     Caco, 
of  calcium  and  chloride  of  ammonium,  as  directed  farther  on.        HN4ci. 

The  chloride  of  ammonium,  which  is  so  troublesome  in  alkali 
determinations,  may  be  decomposed*  very  easily  by  evaporating 

*  J.  L.  Smith,  Am.  Jour.  Sci.  and  Art,  1871,  3d  Ser.,  vol.  i.  (whole  No.  ci.)  p.  269. 

15 


2i 8  THE    CHEMICAL   ANALYSIS   OF  IRON. 

Decomposi-    the  solution  down  very  low,  transferring  to  a  tall  beaker  or  flask, 

tion  of 

NH4ciby  and  heating  with  a  large  excess  of  HNO3, — 3  or  4  c.c.  HNO3  to 
every  gramme  of  NH4C1  supposed  to  be  present.  The  decom- 
position takes  place  at  a  temperature  below  the  boiling-point  of 
water,  and  when  the  action  seems  to  be  over,  transfer  to  a  porce- 
lain dish,  and  evaporate  to  dryness  after  adding  a  few  drops  of 
H2SO4.  Dissolve  in  water,  filter  into  a  platinum  dish,  and  pro- 
ceed with  the  analysis  in  the  usual  way. 


DETERMINATION    OF    CARBONIC   ACID. 

Description  Weigh    3    grammes    of   finely-ground    ore   into    the   flask   A, 

of  the 

apparatus.  Fig.  85,  and  connect  the  apparatus  in  the  manner  shown  in  the 
sketch.  L,  L  are  tubulated  bottles  for  forcing  a  current  of  air 
through  the  apparatus.  The  air  is  deprived  of  any  CO2  which  it 
may  contain  by  passing  through  the  tube  M,  which  is  filled  with 
lumps  of  caustic  potassa.  M  is  connected  with  the  bulb-tube  B  by 
the  tube  N,  a  piece  of  gum  tubing  over  the  slightly  tapering  end 
making  an  air-tight  connection  with  B.  The  tube  O  is  empty, 
and  serves  merely  to  condense  the  mass  of  the  steam  from  the 
flask  A.  P  contains  pumice  saturated  with  anhydrous  CuSO4, 
and  Q  contains  chloride  of  calcium.  The  potash-bulb  and  the 
drying-tube  R  form  the  absorption  apparatus,  and  S  is  a  safety- 
tube  filled  with  CaCl2  to  prevent  R  from  absorbing  moisture  from 
the  atmosphere.  Weigh  the  absorption  apparatus  with  the  pre- 
cautions mentioned  on  page  119,  and  connect  the  apparatus. 
Details  Close  the  stopcock  C,  and  draw  a  little  air  through  the  apparatus 

method.  by  means  of  a  piece  of  gum  tubing  attached  to  the  end  of  S. 
Allow  the  tension  of  the  air  to  draw  the  solution  up  into  the  rear 
limb  of  the  potash-bulb,  and  if  it  remains  there  for  a  reasonable 
length  of  time  the  connections  may  be  considered  tight.  Pour 
into  the  bulb  B  10  c.c.  H2SO4  diluted  with  about  65  c.c.  water, 


ANAL  YSIS   OF  IRON  ORES. 


2IQ 


220  THE   CHEMICAL   ANALYSIS   OF  IRON. 

connect  the  tube  N,  and  by  means  of  the  stopcock  C  allow  the 
acid  to  flow  slowly  into  the  flask  A.  When  the  acid  has  all  run 
in,  by  opening  slightly  the  stopcock  in  L,  start  a  slow  current  of 
air  through  the  apparatus.  Warm  the  flask  A,  gradually  increas- 
ing the  heat  until  the  solution  boils,  and  continue  the  application 
of  heat  until  a  considerable  amount  of  water  has  condensed  in  O, 
Allow  it  to  cool  while  the  current  of  air  is  continued,  detach,  and 
weigh  the  absorption  apparatus.  The  increase  of  weight  is  the 
co2.  weight  of  CO2. 


DETERMINATION     OF     COMBINED    WATER     AND 
CARBON    IN    CARBONACEOUS    MATTER. 

The  ores  are  very  rare  indeed  in  which  the  combined  water 

can  be  accurately  determined  by  simply  heating  them  in  a  cruci- 

LOSS  by         ble   and   calling   the   loss  by  ignition  "  Water  of  Composition." 

ignition.  , 

Nor  is  the  method  of  absorbing  the  moisture,  driven  off  by  heat, 

in  a  drying-tube  much  more  reliable.     The  presence  of  pyrites,  of 

organic  matter,  of  graphite,  and  of  binoxide  of  manganese  serves  to 

Combustion    complicate  the  problem.     The  water  of  composition  may  indeed 

with  chro- 

mate  of      be  determined  with  great  accuracy  by  heating  the  ore  in  a  tube 
with  chromate  of  lead  and  bichromate  of  potassium,  exactly  as  de- 


water. 


mate  of      scribed  for  the  determination  of  carbon  in  iron  and  steel  by  direct 

potassium.  * 

combustion,  page  109  etscq.  The  increase  of  weight  of  the  U  tube 
which  is  attached  to  the  end  of  the  combustion-tube  (and  which 
should  be  filled  in  this  case  with  granulated  dried  CaCl2)  is  the 
Combined  weight  of  "Combined  Water"  in  the  amount  of  ore  used.  By 
attaching  the  absorption  apparatus  we  likewise  obtain  the  total 
CO2  in  the  ore,  or  that  existing  as  CO2  in  the  carbonates,  and 
that  due  to  the  oxidation  of  any  carbon  existing  as  carbonaceous 
or  organic  matter  or  as  graphite.  By  subtracting  from  the  weight 
of  CO2  thus  obtained  the  amount  of  CO2  existing  as  carbonate 
and  determined  by  the  method  last  given,  and  multiplying  the 


ANALYSIS   OF  IRON  ORES. 


221 


difference  by  .27273,  we  get  the  weight  of  "  Carbon  in  carbona-  Carbon  in 
ceous  matter."     When  it  is  necessary  to  make  a  large  number  of     ^Hli 
these  determinations,  the  matter  is  very  much  simplified  by  using 
the  apparatus   shown  in  Figs.  86  and  87.*     Fig.  86  shows  the 
details  of  a  form  of  tubulated  platinum  crucible  suggested  by  Dr.  Tubulated 
Gooch,  which  consists  of  the  crucible  with  a  flange  at  d  into  which 
fits  the  cap.     This  cap  consists  of  a  conical  cover,  H,  drawn  up 

FIG.  86. 


5 

J  INCHES 


vertically  into  the  tube  I.  The  horizontal  tube  J  is  burned  into  I, 
and  through  the  centre  of  I  passes  the  small  tube  K,  which, 
expanding  at  a,  is  burned  into  I  at  this  point,  sealing  it  securely. 
The  tubes  N  and  M  of  glass  are  fused  to  K  and  J  at  C  and  b 
respectively.  In  analyzing  ores  containing  much  water  or  car- 
bonic acid,  use  I  gramme  ;  for  others,  use  3  grammes.  Weigh  the  Details 
finely-ground  ore  into  a  small  agate  mortar,  and  mix  it  thoroughly 
with  7  to  10  grammes  of  previously  fused  bichromate  of  potas- 
sium, transfer  it  to  the  crucible  A,  Fig.  87,  and  place  it  in  an  air-bath 

*  Tenth  Census  of  the  U.  S.,  Mining  Industries,  vol.  xv.  p.  519. 


of  the 
method. 


222 


THE   CHEMICAL   ANAL  YSIS   OF  IRON. 

heated  to  100°  C.  to  drive  off  any  hygroscopic  moisture.  When 
perfectly  dry,  attach  the  cap  B  to  the  crucible,  and  stand  the  latter 
in  the  triangle  C.  Close  the  end  N  with  a  piece  of  rubber  tubing 
in  the  other  end  of  which  is  fitted  a  piece  of  glass  rod.  Attach 
the  weighed  drying-tube  D,  filled  with  CaCl2,  to  the  horizontal 
tube  from  B,  by  means  of  a  thoroughly  dried  velvet  cork.  Attach 
the  absorption  apparatus  E  and  F  and  the  safety-tube  G.  Fill  the 
outside  of  the  flange  d  with  small  pieces  of  fused  tungstate  of 

FIG.  87. 


sodium,  and,  with  a  blow-pipe  flame,  melt  them,  having  previously 
immersed  the  lower  end  of  A  in  a  small  beaker  of  ice-water.  The 
expansion  of  the  air  in  the  crucible  by  the  heat  applied  to  melt  the 
tungstate  of  sodium  will  force  some  bubbles  through  the  potash- 
bulb  E,  and  the  subsequent  cooling  of  the  air  in  A  will  cause  the 
liquid  in  E  to  flow  back  into  the  rear  bulb.  If  the  difference  of 
level  thus  produced  be  maintained  for  some  minutes,  the  connec- 
tions may  be  considered  tight.  Connect  N  with  the  bottles  L,  as 
shown  in  the  sketch,  and  start  a  current  of  air  through  the  appara- 
tus. The  air  is  purified  from  CO2  and  moisture  by  passing  through 
Q,  which  is  filled  with  fused  caustic  potassa.  Now,  by  means  of  the 


ANALYSIS   OF  IRON  ORES. 

blast-lamp  P,  heat  the  crucible  just  above  the  top  of  the  mixture, 
and  gradually  carry  the  heat  downward,  increasing  it  at  the  same 
time.  This  will  keep  the  mixture  from  frothing  and  choking  the 
tube.  Finally,  heat  the  bottom  of  the  crucible  by  the  burner  O,  and 
continue  the  application  of  the  heat  for  ten  minutes.  During  the 
whole  of  the  operation  the  air  passes  through  N  and  K  into  the 
crucible  and  out  through  J  and  M  (Fig.  86)  into  D  (Fig.  87), 
and  so  through  the  apparatus.  The  moisture  from  the  ore  should 
not  be  allowed  to  condense  in  the  wide  part  of  D  at  /,  but  should 
be  driven  forward  into  the  CaCl2  by  warming  the  tube  at  /  with 
the  flame  from  an  alcohol  lamp.  Allow  the  apparatus  to  cool 
while  the  current  of  air  is  continued,  then  detach,  and  weigh  the 
tube  D  and  the  absorption  apparatus,  and  calculate  the  results,  as 
directed  on  page  220.  When  detached  from  the  apparatus,  the 
wide  end  of  the  tube  D  may  be  closed  by  a  short  cork,  covered 
with  tin-foil  to  prevent  the  absorption  of  moisture  from  the  atmos- 
phere. To  clean  the  crucible,  remove  it  from  the  stand,  and,  hold-  cleaning  the 
ing  it  in  a  piece  of  asbestos  board  in  an  inclined  position,  melt  the 
tungstate  of  sodium  in  the  flange  d  with  a  blow-pipe  flame  and 
detach  the  cap.  Dissolve  out  the  bichromate  by  placing  the  cruci- 
ble in  a  dish  of  hot  water,  clean  out  the  ore,  dissolve  any  adhering 
oxide  in  HC1,  wash  the  crucible  and  cap  with  hot  water,  dry  them, 
and  they  will  be  ready  for  another  determination. 


DETERMINATION    OF    CHROMIUM. 

The  small  amount  of  chromium  which  is  found  in  some  iron 
ores  is  generally  converted  into  chromate  of  sodium  very  readily 
by  fusion  with  Na2CO3  and  KNO3.  Fuse  I  or  2  grammes  of  the 
finely-ground  ore  with  10  times  its  weight  of  NagCOg  and  a  little 
KNO3.  Treat  the  fused  mass  with  water  and  wash  it  out  into 
a  small  beaker.  If  the  solution  is  colored  by  manganese,  add  a 


224 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


indication      little   alcohol,  which  will  precipitate  the  manganese,  leaving  the 

of  the 

presence  solution,  if  chromium  is  present,  slightly  yellow.  If  the  solution 
mium.  is  colorless  it  may  be  considered  proof  of  the  absence  of  chro- 
mium. Otherwise  filter,  wash  the  insoluble  matter  on  the  filter, 
dry  it,  grind  it  with  10  times  its  weight  of  Na2CO3  and  a  little 
KNO3,  fuse  it,  treat  with  water  as  before,  filter,  and  add  this  filtrate 
to  the  other.  Acidulate  the  combined  filtrates  with  HC1,  evaporate 
to  dryness  to  render  the  silica  insoluble,  and  reduce  the  chromic 
acid  to  Cr2O3.  Treat  the  mass  with  HC1,  dilute,  filter,  and  precipi- 
tate the  Cr2O3  +  A12O3  by  ammonia.  Boil  for  some  minutes,  filter, 
wash  well  with  hot  water,  dry,  and  ignite  the  precipitate.  Fuse 
with  as  little  Na2CO3  and  KNO3  as  possible,  treat  with  water,  and 
Separation  wash  the  solution  into  a  platinum  dish.  Evaporate  the  solution 

from 

Ai2o3.  until  it  is  very  concentrated,  adding  from  time  to  time  crystals  of 
nitrate  of  ammonium  to  change  all  the  carbonated  and  caustic 
alkali  to  nitrate.  At  each  addition  of  the  nitrate  of  ammonium 
the  solution  effervesces,  and  carbonate  of  ammonium  is  given  off. 
When  the  solution  is  nearly  syrupy,  the  addition  of  nitrate  of  am- 
monium no  longer  causes  an  effervescence,  and  the  solution  smells 
faintly  of  ammonia,  add  a  few  drops  of  NH4HO,  and  filter.  By 
this  operation  all  the  alumina,  phosphate  of  aluminium,  oxide  of 
manganese,  etc.,  are  precipitated,  and  there  remain  in  solution 
only  the  alkalies  and  the  chromate  of  the  alkalies.  To  the  fil- 
trate add  an  excess  of  sulphurous  acid  in  water,  which  instantly 
changes  the  color  of  the  solution  from  yellow  to  green.  Boil  well, 
add  an  excess  of  ammonia,  boil  for  a  few  minutes,  filter  on  an 
ashless  filter,  wash  well  with  hot  water,  dry,  ignite,  and  weigh 
as  Cr2O3. 

Chrome  iron  ore  is  best  decomposed  by  Genth's*  method  of 
fusing  .5  gramme  of  very  finely  ground  ore  with  bisulphate  of 
potassium,  raising  the  heat  very  gradually  until  finally  the  highest 
temperature  of  the  lamp  is  attained,  allowing  it  to  cool,  adding 


Cr203. 

Chrome 
iron  ore. 


*  Chem.  News,  vol.  vi.  p.  31. 


ANALYSIS   OF  IRON  ORES. 


5  grammes  Na2CO3  and  I  gramme  KNO5,  and  heating  gradually 
to  complete  fusion,  allowing  it  to  remain  so  for  fifteen  or  twenty 
minutes,  treating  with  water,  and  proceeding  as  directed  above. 


DETERMINATION    OF   TUNGSTEN. 

Digest  from  i  to  10  grammes  of  the  ore  in  HC1,  adding  HNO3 
from  time  to  time.  When  the  ore  appears  to  be  perfectly  decom- 
posed, evaporate  to  dryness  on  the  water-bath  (a  higher  tem- 
perature is  not  admissible,  as  it  may  render  the  WO3  insoluble 
in  NH4HO),  redissolve  in  HC1,  and  evaporate  down  again.  Re- 
dissolve  in  HC1,  dilute,  filter,  wash  with  acidulated  water,  and 
finally  with  alcohol.  Treat  on  the  filter  with  ammonia,  allowing 
the  filtrate  to  run  into  a  platinum  dish,  evaporate  to  small  bulk, 
add  excess  of  ammonia,  filter,  if  necessary,  into  a  platinum  cru- 
cible, evaporate  carefully  to  dryness,  heat  gently  to  drive  off  the 
ammonia,  and  ignite.  Weigh  as  WO3. 


DETERMINATION    OF   VANADIUM. 

Fuse  5  grammes  of  the  very  finely  ground  ore  with  30 
grammes  of  Na2CO3  and  from  I  to  5  grammes  of  NaNO3,  and 
proceed  exactly  as  in  the  determination  of  vanadium  in  pig-iron, 
page  169.  A  second  fusion  of  the  residue  from  the  aqueous 
solution  of  the  first  fusion  is  hardly  ever  necessary. 


226 


THE   CHEMICAL  ANALYSIS   OF  IRON. 


Hogarth's 
flask. 


Its  advan- 
tages. 


FIG. 


DETERMINATION    OF    SPECIFIC    GRAVITY. 

The  specific  gravity   of  iron    ores   is   determined  with    much 
greater  accuracy  by  using  the  powdered  material  than  by  using 

lumps  of  the  ore.  The  little  flask 
shown  in  Fig.  88  was  designed  for 
this  purpose  'by  the  late  Mr.  James 
Hogarth,*  and  its  use  avoids  two 
difficulties  experienced  in  the  use  of 
the  ordinary  specific  gravity  bottle, — 
the  expansion  and  overflow  conse^ 
quent  upon  transferring  the  flask  at 
60°  F.  to  the  higher  temperature  of 
the  balance-case,  and  the  necessity  for 
waiting  until  the  finely-divided  parti- 
cles of  the  ore  shall  have  settled  before 
inserting  the  stopper.  These  difficul- 
ties were  overcome  by  melting  a  capil- 

lary  tubulus  to  the  lower  part  of  the 

neck  of  the  flask,  and  by  grinding  in 

a  stopper  having  a  small  bulb  above  the  capillary,  to  allow  for 
expansion.  The  operation  is  conducted  as  follows.  Transfer  a 
weighed  amount  of  the  ore  to  the  flask,  add  enough  water  to 
cover  it,  and  heat  it  almost  to  the  boiling-point  by  placing  it  in 
the  water-bath.  Place  the  flask  under  a  bell-jar  connected  with 
an  aspirator  or  air-pump,  and  expel  all  the  air  by  allowing  it  to 
boil  for  some  time  at  a  reduced  pressure.  Remove  it  from  the 
bell-jar,  fill  it  up  to  the  tubulus  with  cold  water,  insert  the  stopper, 
and  cool  the  flask  and  its  contents  to  about  60°  F.  By  suction 
on  the  stopper  draw  water  through  the  tubulus  until  it  is  slightly 
above  the  capillary  of  the  stopper,  at  which  point  a  mark  is 
scratched.  When  the  flask  and  its  contents  are  exactly  at  60°  F., 


Tenth  Census  of  the  U.  S.,  vol.  xv.  p.  522. 


ANALYSIS   OF  IRON  ORES. 

adjust  the  volume  exactly  to  the  mark  on  the  capillary  by  touch- 
ing a  piece  of  blotting-paper  to  the  end  of  the  tubulus  or  by  draw- 
ing a  little  water  in  through  it.  Dry  the  flask,  allow  it  to  acquire 
the  temperature  of  the  balance-case,  and  weigh  it.  Now,  if  W  is 
the  weight  of  ore  taken,  W7  the  weight  of  the  ore  and  water  at 
60°  F.,  and  K  the  weight  of  the  flask  and  its  contents  to  the  mark 
of  water  at  60°  F.,  then 

W 

sp.  gr.  = 

W  +  K— W 

To  obtain  K,  fill  the  flask  with  boiled  water,  and  treat  it  exactly 
as  described  above. 


METHODS  FOR  THE  ANALYSIS 


OF 


LIMESTONE. 


Insoluble 
Silicious 
Matter. 

Resolution 
of  the 
first  pre- 
cipitate 
ofA!203 
and  Fe2O3. 


A12O3  and 
Fe203. 

Quantity  of 
oxalate  of 
ammo- 
nium ne- 
cessary. 


DETERMINATION  OF  INSOLUBLE  SILICIOUS 
MATTER,  ALUMINA  AND  OXIDE  OF  IRON, 
CARBONATE  OF  CALCIUM,  AND  CARBONATE 
OF  MAGNESIUM. 

WEIGH  I  gramme  of  the  powdered  limestone,  previously  dried 
at  1 00°  C.,  into  a  No.  I  beaker,  cover  with  a  watch-glass,  and 
pour  in  5  c.c.  of  HC1  diluted  with  25  c.c.  of  water  and  a  little 
bromine-water.  Digest  on'  the  sand-bath  until  all  the  action 
ceases,  wash  the  watch-glass  off  with  a  fine  jet  of  water,  and  evap- 
orate to  dryness.  Redissolve  in  10  c.c.  HC1  diluted  with  50  c.c. 
water,  filter  on  a  small  ashless  filter,  wash  well  with  hot  water, 
dry,  ignite,  and  weigh  as  Insoluble  Silicions  Matter.  Heat  the  fil- 
trate to  boiling,  add  a  slight  excess  of  ammonia,  boil  for  a  few 
minutes,  filter,  wash  once  or  twice.  Dissolve  the  precipitate  on 
the  filter  in  a  little  dilute  HC1,  allowing  the  solution  to  run  into 
the  beaker  in  which  the  precipitation  was  made,  wash  well  with 
water,  dilute,  boil,  and  reprecipitate  by  ammonia.  Filter  on  a 
small  ashless  filter,  allow  this  filtrate  to  run  into  the  beaker  con- 
taining the  first  one,  wash  well  with  hot  water,  dry,  ignite,  and 
weigh  as  A12O3  and  Fe2O3.  Heat  the  united  filtrates  to  boiling, 
add  enough  oxalate  of  ammonium  to  convert  all  the  calcium  and 
magnesium  into  oxalates.*  Allow  the  precipitate  of  oxalate  of 


25  c.c.  of  the  saturated  solution  is  about  the  proper  quantity. 


228 


ANAL  VSIS  OF  LIMESTONE.  22O 

calcium  to  settle  for  fifteen  or  twenty  minutes,  filter  on  an  ash- 
less  filter,  wash  with  hot  water,  dry,  ignite  for  some  time  over  a 
Btmsen  burner,  and  finally  for  fifteen  minutes  at  the  highest  tem- 
perature of  a  blast-lamp.      Cool  in  a  desiccator,  weigh   quickly, 
ignite  again  over  the  blast-lamp  for  five  minutes,  cool,  and  weigh 
again.      If  this  weight  is  the   same,  or  nearly  the  same,  as  the 
previous   one,   call   the   amount   CaO.     If  the   second  weight  is  cao. 
much  less  than  the  first,  ignite,  and  weigh  again  until  the  weight 
is  constant.     The  weight  of  CaO  multiplied  by  1.7857  gives  the 
weight  of  CaCO3.     Add  to  the  filtrate  from  the  oxalate  of  cal-  Caco3. 
cium  30  c.c.  of  a  saturated  solution  of  microcosmic  salt  (phos-  Quantity  of 
phate  of  sodium  and  ammonium),  acidulate  with  HC1,  and  evap-     micsait 
orate  the  solution  to  about  300  c.c.      If  during  the  evaporation 
any  precipitate  should  separate  out,  redissolve  it  in  HC1.     Cool 
the  evaporated  solution  in  ice-water,  and  add  ammonia  drop  by 
drop,  stirring    the   solution,  but  being  careful  to   avoid  rubbing 
the    sides   of   the    beaker   with    the    rod,   as   the   precipitate   of 
Mg2(NH4)2P2O8-f  I2H2O  is  liable  to  adhere  with  great  tenacity 
to  those  points  or  lines  where  the  rod  has  touched  the  sides  or 
bottom  of  the  beaker.     Continue  the  addition  of  ammonia  until 
the  solution  is  decidedly  alkaline,  and  then  add  an  amount  equal  to 
one-fourth  of  the  neutralized  solution.     After  the  precipitate  has 
begun  to  form,  stir  vigorously  several  times,  allow  to  stand  over- 
night, filter  on  an  ashless  filter,  rub  off  with  a  "policeman"  any 
of  the   precipitate  that  may  adhere  to  the  beaker,  wash  with  a 
mixture  of   I   part   ammonia  and    2  parts  water,  containing   100 
grammes  of  nitrate  of  ammonium  to  the  litre,  dry,  ignite  with 
great  care,  as  directed  on  page  77,  cool,  and  weigh  as  Mg2P2O7, 
which  multiplied  by  .36036  gives  the  weight  of  MgO,  and  multi-  MgOand 
plied  by  .75676  gives  the  weight  of  MgCO3. 


Limestones,    besides    the    ordinary    constituents     mentioned 

above,  may  contain  small  amounts  of  phosphoric  acid,  sulphur     found  in 

.  lime- 

as  sulphate  or  as  pyrites,  titanic  acid,  organic  matter,  combined     stones. 

water,  alkalies,  manganese,  fluorine,  and  in  rare  instances  nearly 


230 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Determina- 
tion of 
Si02. 


Fe203. 
A1203. 


CaO  and 

MgOin 
Insoluble 
Silicious 
Matter. 
Determina- 
tion of 
P205. 


all  the  metals  found  in  iron  ores.  For  most  of  these  the  methods 
described  in  the  analysis  of  iron  ores  may  be  employed.  Very 
often  the  amounts  of  silica  and  alumina  are  required  in  calculating 
mixtures  for  the  blast-furnace,  and,  as  the  matter  insoluble  in  HC1 
consists  usually  of  silicates  of  alumina,  lime,  and  magnesia,  it 
would  be  necessary  in  accurate  work  to  decompose  the  Insoluble 
Silicious  Matter  by  fusion  with  carbonate  of  sodium  and  to  make 
a  separate  analysis  of  it,  as  described  on  page  200.  It  is,  indeed, 
much  better  to  make  the  analysis  in  this  way  than  to  add  the 
filtrate  from  the  silica  to  the  main  solution,  for  the  oxalate  of 
calcium  is  sure  to  carry  down  some  of  the  sodium  salts  with  it 
and  thus  very  materially  complicate  the  analysis. 

After  weighing  the  A12O3  and  Fe2O3  from  the  Insoluble  Silicious 
Matter  and  that  from  the  portion  soluble  in  dilute  HC1  to  deter- 
mine the  Fe2O3,  fuse  the  two  precipitates  with  a  little  carbonate 
of  sodium,  dissolve  in  water,  acidulate  with  HC1  in  a  beaker,  add 
a  few  small  crystals  of  citric  acid  to  the  clear  solution,  then  excess 
of  ammonia  and  sulphide  of  ammonium.  Allow  the  precipitate  of 
sulphide  of  iron  to  settle,  filter,  wash  slightly,  dissolve  in  HC1,  add 
a  little  bromine-water,  boil  the  solution,  precipitate  by  ammonia, 
filter,  wash,  ignite,  and  weigh  as  Fe2O3.  The  weight  of  Fe2O3 
subtracted  from  the  weight  of  the  total  A12O3+  Fe2O3  gives,  of 
course,  the  weight  of  A12O3. 

The  CaO  and  MgO  in  the  Insoluble  Silicious  Matter  should  not 
be  calculated  as  carbonates,  but  should  be  considered  as  existing 
as  CaO  and  MgO. 

To  determine  phosphoric  acid  in  limestones,  treat  20  grammes 
with  dilute  HC1,  filter  from  the  Insoluble  Silicious  Matter,  to  the 
filtrate  add  a  few  drops  of  ferric  chloride  solution,  then  ammonia 
until  the  solution  is  alkaline  to  litmus-paper,*  and  acetic  acid  to 
decided  acid  reaction.  Boil  for  a  few  minutes,  filter,  wash  once 


*  If  the  precipitate  is  not  decidedly  red  in  color,  acidulate  with  HC1  and  add 
more  ferric  chloride  solution. 


ANALYSIS   OF  LIMESTONE. 

with  hot  water,  dissolve  in  HC1  on  the  filter,  allowing  the  solution 
to  run  into  the  beaker  in  which  the  precipitation  was  made,  add 
the  solution  from  the  treatment  of  the  Insoluble  Silicious  Matter 
mentioned  below,  dilute,  and  reprecipitate  exactly  as  before  with 
ammonia  and  acetic  acid.  Dissolve  this  precipitate  on  the  filter 
in  dilute  HC1,  allowing  the  solution  to  run  into  a  No.  I  beaker, 
wash  the  filter  with  hot  water,  evaporate  the  solution  down  almost 
to  dryness,  and  precipitate  the  P2O5  as  directed  on  page  76. 

Ignite  the  Insoluble  Silicious  Matter,  treat  it  with  HF1  and  a  Treatment 
few  drops  of  H2SO4,  evaporate  until  fumes  of  SO3  are  given  off,     soluble 
fuse  with  Na2CO3,  digest  in  water,  filter,  acidulate  the  solution     ™*™s 
with  HC1,  and  add  it  to  the  solution  of  the  first  precipitate  in  the 
soluble  portion  as  mentioned  above. 

Instead  of  treating  the  Insoluble  Silicious  Matter  with  HF1  and  Treatment  of 
H2SO4,  it  may  be  fused  at  once  t  with    Na2CO3,  the   fused   mass 


treated   with  water,  filtered,  the  filtrate  acidulated,  evaporated  to 
dryness,  redissolved  in  water  slightly  acidulated  with  HC1,  filtered,      fusion- 
and  the  filtrate  added  to  the  solution  of  the  first  precipitate  by 
ammonia  and  acetic  acid  as  above. 

To    determine    sulphur   in    limestone,   fuse    I    gramme   with 


Na2CO3  and  KNO3  exactly  as  in  the  determination  of  sulphur  in 
iron  ores,  page   190  et  seq. 

To  determine  sulphates,  proceed  as  in  the  analysis  of  iron  ores 
for  these  substances,  page  191  et  seq. 


METHODS  FOR  THE  ANALYSIS 


OF 


CLAY. 


Composi-  CLAY  is  essentially  silica,  mixed  with  silicates  of  aluminium, 

day.  calcium,  magnesium,  potassium,  and  sodium.  These  silicates  are 
hydrated,  so  that  clay  usually  contains  from  6  to  12  per  cent,  of 
water  of  composition.  Besides  these  usual  constituents,  clay  may 
contain  oxide  of  iron,  titanic  acid,  pyrites,  organic  matter,  phos- 
phoric acid,  and  occasionally  some  of  the  rarer  elements,  such 
as  vanadium. 

Method  of  Clay  being  practically  unacted  on  by  HC1,  it  is  necessary  to 

analysis. 

proceed  as  follows  :  Fuse  I  gramme  of  the  finely-ground  clay 
dried  at  100°  C.  with  10  grammes  of  Na2CO3  and  a  very  little 
NaNO3.  Run  the  fused  mass  well  up  on  the  sides  of  the  crucible, 
allow  it  to  cool,  and  treat  it  with  hot  water  until  thoroughly  disin- 
tegrated, transferring  the  liquid  from  time  to  time  to  a  platinum 
dish.  Treat  the  crucible  with  HC1,  add  this  to  the  liquid  in  the 
dish,  acidulate  with  HC1,  and  evaporate  to  dryness  in  the  air-bath. 
Treat  the  mass  with  water  and  a  little  HC1,  evaporate  again  to 
dryness,  and  treat  with  15  c.c.  HC1  and  45  c.c.  water.  Allow  it 
to  stand  in  a  warm  place  for  fifteen  or  twenty  minutes,  add  50 
c.c.  water,  and  filter  on  an  ashless  filter.  Wash  thoroughly  with 
hot  water  acidulated  with  a  few  drops  of  HC1,  dry,  ignite,  heat  for 
three  or  four  minutes  over  the  blast-lamp,  and  weigh.  Treat  the 
precipitate  with  HF1  and  a  few  drops  of  H2SO4,  evaporate  to  dry- 
ness,  ignite,  and  weigh.  The  difference  between  the  two  weights  is 
232 


ANALYSIS   OF  CLAY. 

SiO2.  If  any  appreciable  residue  remains  in  the  crucible,  treat  it  SiO2. 
with  a  little  HC1,  and  wash  it  out  into  the  filtrate  from  the  silica. 
Transfer  the  filtrate  from  the  silica  to  a  large  platinum  dish,  heat 
it  to  boiling,  add  an  excess  of  ammonia,  boil  until  the  smell  of 
NH3  is  quite  faint,  filter  on  an  ashless  filter,  and  wash  several 
times  with  hot  water.  Stand  the  filtrate  and  washings  aside,  and 
treat  the  precipitate  on  the  filter  with  a  mixture  of  15  c.c.  HC1 
and  15  c.c.  water,  cold.  Allow  the  solution  to  run  into  a  small 
clean  beaker,  replace  this  by  the  platinum  dish  in  which  the  pre- 
cipitation was  made,  pour  the  solution  on  the  filter  again,  and 
repeat  this  operation  until  the  precipitate  has  completely  dissolved. 
Wash  out  the  beaker  into  the  filter,  wash  the  latter  thoroughly 
with  cold  water,  dry,  and  preserve  it.  Reprecipitate  by  ammonia, 
as  above  directed,  filter  on  an  ashless  filter,  wipe  out  the  dish  with 
small  pieces  of  filter-paper,  add  these  to  the  precipitate,  and  wash 
thoroughly  with  hot  water.  Dry,  ignite  the  precipitate  and  filter, 
and  the  filter  from  the  first  precipitation,  heat  for  a  few  minutes 
over  the  blast-lamp,  cool,  and  weigh  as  A12O3  and  Fe2O3.  Fuse  Ai2o8  + 
the  ignited  precipitate  with  Na2CO3,  treat  the  fused  mass  with 
water,  wash  it  out  into  a  small  beaker,  allow  the  residue  to 
settle,  decant  off  the.  clear,  supernatant  fluid,  treat  the  residue  with 
HC1,  and  determine  the  iron  volumetrically,  or  add  citric  acid  and 
ammonia,  and  precipitate  the  iron  as  sulphide.  Filter,  wash,  dis- 
solve in  HC1,  oxidize  with  bromine-  water,  and  precipitate  the 
Fe2O3  by  ammonia.  Filter,  wash,  dry,  ignite,  and  weigh  as  Fe2O3. 
Subtract  the  weight  of  Fe2O3  from  the  A12O3  +  Fe2O3  found  above, 
and  the  difference  is  A12O3. 

As  the  amounts  of  calcium  and  magnesium  in  clay  are  very 
small,  the  filtrate  and  washings  from  the  second  precipitation  of 
Al2O3-f  Fe2O3  may  be  rejected  and  the  CaO  and  MgO  deter- 
mined  in  the  first  filtrate  as  directed  on  page  201. 


To  determine  the  alkalies  in  clay,  treat  2  grammes  of  the  finely- 
ground  material  in  a  platinum  dish  with  4  c.c.  of  strong  H2SO4     alkalies. 
and  40  or  50  c.c.  of  redistilled   HF1.     Stir  it  from  time  to  time 

16 


234 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


Decomposi- 
tion by 
HF1  and 
H2SO4. 


Washing 
the  pre- 
cipitated 
A1203. 


J.  Lawrence 
Smith's 
method  for 
alkalies. 


with  a  platinum  wire  or  rod,  heating  carefully,  until  the  clay  is 
entirely  decomposed  and  no  more  gritty  substance  can  be  felt 
under  the  rod.  Evaporate  to  dryness,  and  heat  until  fumes  of 
SO3  are  given  off.  The  entire  operation  should  be  carried  on 
under  a  hood  with  a  good  draft,  as  HF1  is  very  poisonous,  and  the 
evaporation  may  be  safely  conducted  on  the  little  arrangement 
shown  in  Fig.  8,  page  15.  Allow  the  dish  to  cool,  add  about 
50  c.c.  water  and  a  little  HC1,  and  heat  until  the  mass  is  all  dis- 
solved. If  any  of  the  clay  has  escaped  decomposition,  filter  into 
another  platinum  dish,  wash  the  insoluble  matter  on  the  filter, 
dry,  ignite,  and  decompose  it  in  the  crucible  with  HF1  and  H2SO4. 
Dissolve  the  mass  in  the  crucible  after  evaporating  off  the  HF1, 
and  add  the  solution  to  the  main  solution  in  the  dish.  Dilute 
this  solution  to  300  or  400  c.c.  with  hot  water,  heat  to  boiling,  add 
an  excess  of  ammonia,  boil  for  a  few  minutes,  and  filter.  Allow 
the  precipitate  to  drain  well  on  the  filter,  remove  the  filtrate,  which 
should  be  in  a  platinum  dish,  to  a  light,  and  evaporate  it  down. 
Pierce  the  filter  with  a  wire  or  rod,  and  wash  the  precipitate  into 
the  dish  in  which  the  precipitation  was  made  with  a  jet  of  hot 
water.  Dilute  to  300  or  400  c.c.,  add  a  little  ammonia,  heat  to 
boiling,  filter,  and  wash  several  times  with  hot  water.  Add  this 
filtrate  to  the  first  one,  and  evaporate  to  dryness.  Heat  until 
all  the  ammonium  salts  are  volatilized,  and  proceed  exactly  as 
directed  for  the  determination  of  alkalies  in  the  Insoluble  Silicious 
Matter  from  iron  ores,  page  216. 

Instead  of  decomposing  the  clay  by  HF1  and  H2SO4,  the 
method  given  by  J.  Lawrence  Smith  may  be  used  for  determining 
alkalies.  Weigh  I  gramme  of  the  finely-ground  clay  into  a  por- 
celain or  agate  mortar,  add  an  equal  weight  of  granular  chloride 
of  ammonium,*  and  grind  the  two  together  to  mix  them.  Add 
8  grammes  of  carbonate  of  calcium, f  and  grind  the  entire  mass 
so  as  to  obtain  an  intimate  mixture  of  the  whole.  Transfer  to  a 


*  See  page  38. 


f  See  page  45. 


ANALYSIS   OF  CLAY. 


235 


capacious  platinum  crucible,  cover  with  a  close-fitting  lid,  and 
heat  carefully  to  decompose  the  chloride  of  ammonium,  which  is 
accomplished  in  a  few  minutes.  Heat  gradually  to  redness,  and 
keep  the  bottom  of  the  crucible  at  a  bright  red  for  about  an  hour. 
Allow  the.  crucible  to  cool,  and'  if  the  mass  is  easily  detached  from 
the  crucible,  transfer  it  to  a  platinum  dish  and  add  about  80  c.c. 
of  water.  Wash  off  the  lid  into  the  crucible  with  water,  heat  this 
to  boiling,  and  wash  the  crucible  out  into  the  dish.  Heat  the 
water  in  the  dish  to  boiling,  and,  when  the  mass  has  completely 
slaked,  filter  into  another  platinum  dish  and  wash  the  mass  on  the 
filter  with  hot  water.  If  the  semi-fused  mass  in  the  crucible  is  not 
easily  detached,  place  the  crucible  on  its  side  in  the  dish,  wash  off 
the  lid  into  the  dish,  add  about  100  c.c.  water,  and  heat  until  the 
mass  disintegrates.  Remove  the  crucible,  wash  it  off  into  the 
dish,  and  filter  as  above  directed.  To  the  filtrate  add  about  \y2 
grammes  of  pure  carbonate  of  ammonium,  evaporate  on  the 
water-bath,  or  very  carefully  over  a  light,  until  the  volume  of  the 
solution  is  reduced  to  about  40  c.c.,  add  a  little  more  carbonate 
of  ammonium  and  a  few  drops  of  ammonia,  and  filter  on  a  small 
filter.  Evaporate  the  filtrate  carefully  after  adding  a  few  drops 
more  of  carbonate  of  ammonium  to  make  certain  that  all  the  cal- 
cium has  been  precipitated.  If  any  further  precipitate  appears, 
filter  into  a  platinum  crucible  and  evaporate  to  dryness.  Heat 
carefully  to  dull  redness  to  drive  off  any  ammonium  salts,  and 
weigh  the  residue  as  KCl  +  NaCl.  Separate  the  potassium  and 
sodium  as  directed  on  page  217. 

Determine  the  water  of  composition  by  igniting  I  gramme  of  water  of 
the  clay  for  twenty  minutes  at  a  bright  red  heat,  when  the  loss     tioT.P° 
of  weight  will    represent  the  water.      In  the   presence  of  much 
organic  matter  or  pyrites  the  method  given  for  the  determination 
of  water  of  composition  in  iron  ores,  page  220,  may  be  used. 

To    determine    titanic  acid,  treat   2   grammes   of  the    finely-  Determma- 

tion  of 

ground  clay  in   a  large  platinum  crucible  with  HF1  and  5  c.c.     TJOS. 
H2SO4.      Evaporate   off  the    HF1,  and    heat   carefully  until   the 


236  THE   CHEMICAL  ANALYSIS   OF  IRON. 

greater  part  of  the  H2SO4  is  volatilized.  Allow  the  crucible  to 
cool,  add  10  grammes  of  Na2CO3,  and  fuse  for  thirty  minutes  at 
the  'highest  temperature  obtainable  by  a  Bunsen  burner.  Run  the 
fused  mass  well  up  on  the  sides  of  the  crucible,  and  allow  it  to 
cool.  Treat  the  fused  mass  with  water,  transfer  it  to  a  beaker,  and 
filter.  Wash  the  insoluble  matter  slightly  on  the  filter,  dry,  ignite, 
and  fuse  it  again  with  Na2CO3.  Dissolve  in  water  as  before,  and 
filter.  By  this  method  of  treatment  nearly  all  the  alumina  will  be 
dissolved  and  separated  from  the  titanic  acid.  Fuse  the  insoluble 
matter  left  on  the  filter  with  Na2CO3,  and  determine  the  TiO2  as 
directed  on  page  152. 

DtSToT  a~  When  alkalies   are  determined,  the  precipitated  alumina  may 

Tio2in       ke  usecj  f      fae  determination  of  TiO2.     In  this  case  dry  the  pre- 

the  por- 
tion taken    cipitate  of  ALOo,  etc.,   separate   it  from  the  filter,  ignite  the  two 

for  the 

determi-      filters,  add  the  ash  to  the  dried,  not  ignited,  precipitate  of  A12O3, 

nation  of  /-^/~\ 

alkalies,      etc.,  and  fuse  with  Na2CO3  as  above. 


METHODS  FOR  THE  ANALYSIS 


OF 


SLAGS. 


BLAST-FURNACE  slags  contain  silica,  alumina,  lime,  magnesia,  Composition 
and   alkalies    always,   generally   also   ferrous    oxide,   manganous 


oxide,  and  sulphur,  and  occasionally  titanic  acid,  small  amounts 
of  phosphoric  acid,  and  such  metallic  oxides  as  may  exist  in  the 
ores,  fluxes,  or  fuel  used  in  the  furnace.  Sulphur,  which  is  occa- 
sionally present  in  considerable  amounts,  is  considered  to  exist  in 
the  slag  as  sulphide  of  calcium. 

The  method  used  for  the  determination  of  the  principal  in- 
gredients depends  upon  whether  the  slag  is  capable  of  being 
entirely  or  but  partially  decomposed  by  HC1. 

In  the  first  case  weigh  I  gramme  of  the  finely-ground  slag 
into  a  platinum  or  porcelain  dish,  add  20  c.c.  of  water,  and  shake 
the  dish  until  the  material  is  thoroughly  disseminated  through  the 
water.  Add  gradually  30  c.c.  HC1,  with  constant  stirring,  and 


finally  heat  the  dish  carefully.  The  slag  will  dissolve  completely  byHci. 
to  a  clear  liquid,  but,  after  heating  for  a  short  time,  will  suddenly 
form  a  solid  jelly.  Evaporate  carefully  to  dryness,  treat  with  a 
few  c.c.  of  dilute  HC1  and  a  little  bromine-  water,  evaporate  again 
to  dryness,  and  add  15  c.c.  HC1  and  45  c.c.  water.  Allow  to 
stand  fifteen  or  twenty  minutes  in  a  warm  place,  add  50  c.c.  water, 
filter  on  an  ashless  filter,  wash  thoroughly  with  hot  water,  dry, 
ignite,  and  weigh.  Treat  the  material  in  the  crucible  with  a  little 
water,  add  2  or  3  drops  H2SO4  and  enough  HF1  to  dissolve  it. 

237 


THE    CHEMICAL   ANAL  YSIS   OF  IRON. 

Evaporate   to   dryness,   ignite,  and  weigh.      The  loss  of  weight 

sio2.  is  SiO2. 

Non-voiatiie  Any  residue  in  the  crucible  after  the  volatilization  of  the  SiO2 
is  to  be  added  to  the  A12O3  +  Fe2O3.  Heat  the  filtrate  obtained 
above,  diluted  to  500  c.c.,  to  boiling,  add  a  slight  excess  of  ammo- 
nia, boil  for  a  few  minutes,  filter  on  an  ashless  filter,  and  wash  two 
or  three  times  with  boiling  water.  Stand  the  filtrate  aside,  and 
pour  on  the  precipitate  in  the  filter  a  mixture  of  15  c.c.  HC1  and 
30  c.c.  cold  H2O,  allowing  the  solution  to  run  into  the  dish  in 
which  the  precipitation  was  made.  Alumina  precipitated  in  this 

Resolution     wav  seems  generally  to  dissolve  more  readily  in  cold  than  in  hot 

cfpimeT"  dilute  HC1,  but  it  is  often  necessary  to  break  up  the  precipitate  on 

Ai2o8,  etc.  the  filter  with  a  rod,  to  pour  the  acid  solution  back  on  the  filter 

several  times  after  it  has  run  through,  and  sometimes  to  pierce 

the  filter  with  a  rod  or  wire  and  wash  the  precipitate  still  undis- 

Preservadon  solved  into  the  dish.  Wash  the  filter  well  with  water,  dry  it,  and 
filter.  keep  it  to  ignite  with  the  A12O3,  etc.  Heat  the  filtrate  and  wash- 
ings to  boiling,  reprecipitate  by  ammonia,  filter  on  an  ashless  filter, 
clean  off  any  adhering  precipitate  from  the  dish  with  filter-paper, 
add  it  to  the  precipitate  on  the  filter,  wash  well  with  hot  water, 
dry,  ignite,  after  adding  the  filter  on  which  the  first  precipitation 
was  filtered,  and  weigh  as  A12O3,  etc.  Add  to  this  the  weight  of 
the  residue  from  the  treatment  of  the  SiO2  by.  H2SO4  and  HF1,* 

Ai2o3,etc.     and  the  sum  is  the  total  Al2O3-f  Fe2O3+ P2O5  +  TiO2. 

Evaporate  down  the  two  filtrates  obtained  above  to  about  300  c.c., 
transfer  to  a  No.  3  beaker,  add  a  few  drops  of  ammonia  and  enough 
sulphide  of  ammonium  to  precipitate  the  manganese.  Filter  off,  and 

Mno.  determine  the  manganese  as  directed  on  page  203,  in  the  "Analysis 

of  Iron  Ores."     To  the  filtrate  from  the  sulphide  of  manganese  add 
a  slight  excess  of  HC1,  boil  until  all  the  H2S  is  driven  off,  filter  from 

CaO  and  any  precipitated  sulphur,  and  determine  the  CaO  and  MgO  as  di- 
rected on  page  228  et seq.,  in  the  "Analysis  of  Limestone." 

*  This  residue  should  be  examined  for  CaO. 


ANALYSIS   OF  SLAGS. 

To  determine  the   FeO,  fuse  the  ignited  precipitate  of  A12O3, 
etc.,  obtained  above,  with  5   grammes  of  carbonate  of  sodium,  at     FeO° 
a  very  high  temperature,  for  at  least  thirty  minutes.     Allow  the 
crucible  to  cool,  treat  the  fused  mass  with  water,  transfer  to  a 
beaker,  allow  the  insoluble  matter  to  settle,  decant  off  the  clear, 
supernatant  liquid  through  a  filter,  and  treat  the  residue  with  HC1. 
Pour  the  solution  through  the  filter  to  take  up  any  iron  that  may 
have  been  suspended  in  the  liquid  decanted  through  it,  and  deter- 
mine the  iron  volumetrically  or  by  precipitation  as  sulphide  in  the 
solution  to  which  citric  acid  and  an  excess  of  ammonia  have  been 
added,  as  on  page  209.     When  the  slag  contains  no  appreciable  siags  con- 
amount  of  manganese,  the  precipitation  by  sulphide  of  ammonium,     man'gf-0 
page  238,  may  be  omitted  and  the  CaO  precipitated  at  once  from 
the  concentrated  solution. 

For  the  analysis  of  slags  that  are  not  entirely  decomposed  by  siags  that 
HC1,  recourse  must  be  had  to  fusion  with   Na2CO3  and  a  little     entirely 
NaNO3,  exactly  as  described  for  the  analysis  of  clay,  page  232     Jo^ST 
et  seq.     After  filtering  off  the  SiO2  as  directed,  page  232,  proceed     byli 
with  the  analysis  as  described  for  slags  decomposed  by  HC1,  page 
237  et  seq.     As,  however,  the  oxalate  of  calcium  is  very  liable  to 


carry  down  sodium-salts  with  it,  it  is  always  well,  after  igniting  the 
oxalate  of  calcium,  to  dissolve  it  in  dilute  HC1,  transfer  the  solu- 
tion to  a  platinum  dish,  dilute  to  300  c.c.  with  hot  water,  add  an 
excess  of  ammonia,  and  precipitate  boiling  by  30  c.c.  of  a  saturated 
solution  of  oxalate  of  ammonium.  Filter,  wash,  ignite,  and  weigh 
in  the  usual  manner. 

For  the  determination  of  sulphur  in  slags,  fuse  I  gramme  with 

tion  of 

Na2CO3  and  a  little  KNO3,  and  proceed  exactly  as  directed  for  the     sulphur 

in  slags. 

determination  of  sulphur  in  iron  ores,  page  190  et  seq.  Calculate 
the  total  sulphur  as  CaS  and  the  remainder  of  the  calcium  as  CaO. 

For  the  determination  of  alkalies,  titanic  acid,  etc.,  proceed  as  Alkalies, 

TiOj,  etc. 

directed  for  the  determination  of  these  substances  in  clay. 

Converter   slags,  open-hearth  slags,  refinery  slag,  tap  cinder,  Converter 
mill  cinder,  etc.,  are  analyzed  by  the  methods  described  for  the 


240  THE    CHEMICAL   ANALYSIS   OF  IRON. 

Analysis  of    analysis  of  iron   ores.     In  the  case  of  slags    obtained  from  the 

basic  slag. 

manufacture  of  steel  by  the  basic  process,  which  usually  contain 
very  large  amounts  of  phosphoric  acid,  proceed  as  follows  :  Treat 
I  gramme  of  the  finely-ground  slag  in  a  small  beaker  with  1 5  c.c. 
HC1  and  a  little  HNO3  until  it  is  decomposed.  Evaporate  to  dry- 
ness,  redissolve  in  10  c.c.  HC1  and  20  c.c.  H2O,  dilute,  filter  off, 

Si02.  and  weigh  the  SiO2.  To  the  filtrate  diluted  to  500  c.c.  add  a  solu- 

tion of  ferric  chloride  and  a  slight  excess  of  ammonia,  if  the  pre- 
cipitate is  not  decidedly  red  in  color,  acidulate  carefully  with  HC1, 
add  more  ferric  chloride  solution,  and  then  a  slight  excess  of 
ammonia.  Add  acetic  acid  to  slight  acid  reaction,  heat  to  boiling, 
filter  and  wash  slightly  with  boiling  water,  stand  the  filtrate  aside, 
and  dissolve  the  precipitate  on  the  filter  in  HC1,  allow  the  solution 
to  run  into  the  beaker  in  which  the  precipitation  was  made,  wash 
the  filter  thoroughly  with  cold  water,  dilute  the  filtrate  to  about 
400  c.c.,  add  a  slight  excess  of  ammonia,  and  then  acetic  acid, 
boil,  and  filter  as  before.  Add  this  filtrate  to  the  first,  evaporate 
down,  and  determine  the  manganese,  calcium,  and  magnesium,  as 

MnO,CaO,  directed  in  the  case  of  blast-furnace  slags,  page  238.  Dissolve  the 
precipitate  on  the  filter  in  HC1,  dissolving  any  iron  that  may 
adhere  to  the  beaker  in  a  few  drops  of  the  same  acid,  pour  it  on 
the  filter,  and  wash  the  beaker  and  filter  well  with  water.  Allow 
the  solution  and  washings  to  run  into  a  No.  3  beaker,  add  about 
10  grammes  of  citric  acid  and  an  excess  of  ammonia.  To  this 
solution,  which  should  be  cold,  and  should  measure  about  300  c.c., 
add,  drop  by  drop,  50  c.c.  of  magnesia  mixture,  stirring  carefully, 
without  touching  the  sides  of  the  beaker  with  the  rod.  Add  about 
one-third  the  volume  of  the  solution  of  ammonia,  allow  the  beaker 
to  stand  in  ice-water  for  some  time,  stir  vigorously  several  times, 
and  after  a  few  hours  filter  (preferably  on  a  Gooch  crucible),  wash 
with  ammonia-water  of  the  usual  strength,  ignite  carefully,  and 

1*2^5  • 

weigh  as  Mg2P2O7.     Any  alumina  in  the  slag  will  be  in  the  fil- 

A12OS. 

trate  from  the  phosphate  of  ammonium  and  magnesium,  and  may 
be  determined  by  the  method  on  page  209.  Determine  the  iron 


ANALYSIS   OF  SLAGS. 

volumetrically  in  a  separate  portion,  and  calculate  to  FeO.  Deter- 
mine  any  other  elements  present  by  the  methods  under  "  Analysis 
of  Iron  Ores." 

Phosphoric  acid  cannot  well  be  determined  in  basic  slags  by 
fusion  with  NagCOg,  as  phosphate  of  calcium  is  not  readily  decom- 
posed by  this  method,  and  its  employment  may  lead  to  error. 


METHOD  FOR  THE  ANALYSIS 


OF 


FIRE-SANDS. 


As  sand  contains  comparatively  very  small  amounts  of  alumina, 

lime,  and  magnesia,  and  a  very  large  amount  of  silica,  it  is  best 

Treatment     to  proceed  as  follows  in  the  analysis :  Weigh  2  grammes  of  the 

with  HFl 

and  finely-ground    sand    into  a  large    platinum    crucible,    moisten    it 

TT    C(~) 

with  cold  water,  add  6  or  8  drops  of  H2SO4,  and  then  gradually 
enough  HFl  to  dissolve  it.  Evaporate  to  dryness  (under  a  hood, 
of  course),  and  heat  to  redness  to  drive  off  the  H2SO4.  Allow 
the  crucible  to  cool,  add  a  little  Na2CO3,  and  fuse.  Dissolve  the 
cold  fusion  in  water,  add  an  excess  of  HC1,  and  determine  the 
Ai2o8,CaO,  A12O3,  CaO,  and  MgO  as  usual.  Ignite  I  gramme  of  the  sand 

and  MgO. 

Water.          and  determine  the  loss,  which  will  be  water  and  organic  matter  (if 
present). 

Add  together  the  percentages  of  water,  A12O3,  CaO,  and  MgO, 
Sio2.  subtract  the  sum  from   100,  and  call  the  remainder  SiO2. 


242 


METHODS    FOR    THE    ANALYSIS 


OF 


COAL   AND    COKE. 


PROXIMATE    ANALYSIS. 

A  PROXIMATE  analysis  affords  a  very  rapid  and  comparatively 
simple  way  of  classifying  and  valuing  coal.  From  the  nature 
of  the  material,  the  determinations  cannot  be  absolute,  but  infer- 
ences may  be  drawn  from  the  relative  proportions  of  Moisture, 
Volatile  Combustible  Matter,  and  Ash.  Therefore  it  is  essential  that 
the  analysis  should  be  performed  in  such  a  way  as  to  obtain  the 
most  concordant  results.  The  series  of  experiments  carried  out 
by  Prof.  Heinrichs,*  of  the  Iowa  State  Geological  Survey,  show 
very  clearly  that  by  following  a  definite  course  of  procedure  and 
taking  a  few  simple  precautions  the  method  may  be  made  suf- 
ficiently accurate  to  accomplish  satisfactorily  the  desired  object. 
The  details,  which  should  in  all  cases  be  closely  adhered  to,  are 
as  follows :  Weigh  from  I  to  2  grammes  of  powdered  coal  into  a 
crucible,  heat  for  exactly  one  hour  in  an  air-bath  from  105°  to  1 10° 
C,  allow  the  crucible  to  cool,  and  weigh  it.  The  loss  of  weight 
divided  by  the  weight  of  coal  taken  and  the  result  multiplied  by 
100  gives  the  percentage  of  Moisture  in  the  coal.  Weigh  from  I  Moisture. 
to  2  grammes  of  the  powdered  coal  into  a  small  platinum  crucible,  volatile 
heat  the  crucible  with  the  cover  on  by  means  of  a  Bunsen  burner  b^7ibie 
for  three  and  a  half  minutes,  then,  without  allowing  the  crucible  Mat 

*  Chem.  News,  xviii.  53. 

243 


244  THE    CHEMICAL   ANALYSIS   OF  IRON. 

to  cool,  heat  it  for  three  and  a  half  minutes  more  at  the  highest 
temperature  obtainable  by  means  of  a  gas  blast-lamp.     Cool  and 
weigh.     Divide  the  loss  of  weight  by  the  amount  of  material  used, 
multiply  by   100,  subtract  the  percentage  of  Moisture,  and  the  re- 
mainder is  the   percentage  of    Volatile  Combustible   Matter.     This 
^tiottobe     determination  should  always  be  made  on  a  fresh  portion  of  coal, 
used.         ancl  never  on  the  portion  used  for  the  determination  of  Moisture. 

After  weighing  the  crucible  for  the  determination  of  Volatile 
Combustible  Matter  as  above,  place  it  over  a  light  in  the  position 
shown  in  Fig.  10  or  Fig.  n,  page  16,  and  burn  off  the  carbon. 
This  operation,  which  is  liable  to  be  tedious,  may  be  hastened  by 
breaking  up  and  stirring  the  mass  from  time  to  time  with  a 
platinum  rod  or  a  piece  of  stiff  wire.  It  is  necessary  to  avoid  pro- 
Precautions  ducing  too  strong  a  draft  in  the  crucible,  as  by  this  means  par- 

in  burning 

off  car-  tides  of  the  ash  may  be  carried  out  and  a  fictitious  "value  given  to 
the  coal  or  coke  by  the  apparent  increase  of  Fixed  Carbon  and 
corresponding  decrease  of  Ash.  When  no  particles  of  carbon  are 
apparent  in  the  ash,  allow  the  crucible  to  cool,  and  weigh  it. 
The  difference  between  this  weight  and  the  last,  divided  by  the 
weight  of  coal  taken,  and  multiplied  by  100,  gives  the  percentage 

Fixed  Car- 
bon, of  Fixed  Carbon. 

The  difference  between  the  sum  of  the  percentages  of  Water, 

Volatile  Combustible  Matter,  and  Fixed  Carbon  and  100  is  the  per- 

Ash.  centage  of  Ash.     The  sum  of  the  percentages  of  Fixed  Carbon  and 

Coke.  Ash  is  the  percentage  of  Coke  which  the  coal  will  yield.     The 

appearance  of  the  coke  before  burning  off  the  Fixed  Carbon,  its 

hardness,  etc.,  are  often  valuable  indications  of  the  coking  qualities 

of  the  coal,  and  should  be  noted.     The  appearance,  color,  etc.,  of 

the  Ash  should  likewise  be  noted. 


ANALYSIS   OF   THE    ASH. 

The  ash  may  be  analyzed  by  the  method  given  for  the  analysis 
of  the  Insoluble  Silicious  Matter  in  Iron  Ores,  page  200. 


ANALYSIS   OF  COAL   AND    COKE. 

DETERMINATION    OF    SULPHUR. 

Weigh  out  I  gramme  of  the  finely-ground  coal  or  coke,  and  Fusion  with 
mix  it  thoroughly,  by  grinding  in  a  large  agate  or  porcelain  mor-  and 
tar,  with  10  grammes  of  dry  Na2CO3  and  6  grammes  of  KNO3. 
During  the  mixing  it  is  well  to  have  the  mortar  on  a  large  sheet 
of  white  glazed  paper,  to  catch  any  particles  that  may  be  thrown 
from  it.  Transfer  the  mixture  to  a  large  platinum  crucible,  clean 
the  mortar  by  grinding  a  little  Na2CO3  in  it,  transfer  this  and  any 
particles  that  may  be  on  the  paper  to  the  crucible,  cover  the 
latter  with  a  lid,  and  place  it  on  a  triangle  over  a  Bunsen  burner. 
Heat  the  crucible  very  carefully,  and  raise  the  heat  very  slowly, 
cautiously  removing  the  lid  of  the  crucible  from  time  to  time  to 
see  that  the  fusion  does  not  boil  over.  It  is  very  necessary  that 
none  of  the  fused  sodium  or  potassium  salts  be  allowed  to  get  on 
the  outside  of  the  crucible,  for  they  will  certainly  absorb  sulphuric 
or  sulphurous  acid  from  the  burned  gas,  and  thus  vitiate  the  analy- 
sis. When  the  mass  in  the  crucible  is  in  a  tranquil  state  of  fusion, 
run  it  up  on  the  sides  of  the  crucible,  allow  it  to  cool,  treat  it  with 
hot  water,  and  wash  it  out  into  a  small  clean  beaker.  Filter  from 
the  insoluble  matter,  acidulate  the  filtrate  with  HC1,  and  evaporate 
to  dryness.  Redissolve  in  water  with  a  few  drops  of  HC1,  filter, 
dilute  the  filtrate  to  about  500  c.c.,  heat  to  boiling,  and  add  10-20 
c.c.  solution  of  chloride  of  barium.*  Allow  the  precipitated  sulphate 
of  barium  to  settle,  decant  the  clear,  supernatant  fluid  through  a  washing  the 

sulphate 

filter  or  through  a  felt  on  a  Gooch  crucible,  heat  the  precipitate     Of  barium, 
with  a  solution  of  acetate  of  ammonium,t  transfer  it  to  the  filter, 
wash  well  with  hot  water,  dry,  ignite,  and  weigh  as  BaSO4,  which, 
multiplied   by  .1373,  gives  the  weight  of  S.     The  time  of  the  Method  of 
operation  may  often  be  very  much  shortened  by  adding  an  excess     *ngthe 
of  ammonia  to  the  acidulated  filtrate  of  the  aqueous  solution  of     oper: 
the  fusion,  and   boiling   the  solution  while  passing  through  it  a 
rapid  current  of  carbonic  acid  gas.     This  precipitates  the  silica, 

*  See  page  44.  t  See  page  39. 


246 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Correction 
for  S  in 
reagents. 


Eschka's 
method. 


Method  of 
report- 
ing the 
amount 
of  S  in  a 
coal. 


alumina,  etc.,  and,  after  filtering  this  off,  acidulate  by  HC1,  and 
precipitate  the  sulphate  of  barium,  as  above  directed. 

A  blank  determination,  using  the  same  amount  of  Na2CO3, 
KNO3,  and  HC1,  should  always  be  made  with  every  new  lot  of 
reagents,  and  the  amount  of  BaSO4  found,  subtracted  from  the 
amount  of  BaSO4  in  every  analysis  before  calculating  the  amount 
of  S  in  the  coal  or  coke. 

Besides  the  method  given  above,  Eschka's*  method  is  very 
often  used.  It  is  essentially  as  follows :  Weigh  out  I  gramme  of 
the  finely-ground  sample,  and  mix  it  thoroughly  in  a  mortar  with 
I  gramme  of  calcined  magnesia  and  .5  gramme  of  dry  carbonate 
of  sodium,  transfer  the  mixture  to  a  crucible,  and  heat  it  over  a 
Bunsen  burner,  having  the  crucible  inclined  in  such  a  way  that  the 
flame  may  be  applied  to  the  bottom  of  the  crucible,  so  that  the  heat, 
a  dull  red,  shall  extend  only  about  one-third  up  from  the  bottom. 
Stir  the  mixture  every  few  minutes  with  a  platinum  wire  until  the 
carbon  is  burned  off  and  the  ash  is  a  dull  yellow.  This  will  gen- 
erally require  about  one  hour.  Allow  the  crucible  to  cool,  add  to 
the  mixture  about  I  gramme  of  nitrate  of  ammonium,  mix  it  in 
thoroughly  with  a  glass  rod,  place  the  lid  on  the  crucible,  and  heat 
it  cautiously  until  the  nitrate  of  ammonium  is  decomposed  and 
the  crucible  is  raised  to  a  bright  red  heat.  Allow  it  to  cool,  treat  it 
with  hot  water,  and  transfer  the  contents  to  a  beaker.  Filter  from 
the  insoluble  matter,  acidulate  the  filtrate  with  HC1,  and  determine 
the  S  by  precipitation  as  BaSO4  in  the  usual  way. 

In  reporting  the  results  of  a  coal  analysis  the  S  should 
always  be  reported  as  a  separate  matter,  and  no  attempt  should 
be  made  to  distribute  it  between  the  Volatile  Combustible  Matter, 
Fixed  Carbon,  and  Ash.  The  reason  for  this  is  obvious  when  we 
consider  the  conditions  in  which  S  exists  in  coal,  and  the  diffi- 
culty which  attends  any  attempt  to  determine  the  amount  existing 
in  any  one  condition. 


*  Chem.  News,  xxi.  261. 


ANALYSIS   OF  COAL   AND   COKE.  247 

Sulphur  is  known  to  exist  in  coal  in  three  conditions, — as  a  Condition 

•« .  «    •••  _4  1  .  in  which 

metallic  sulphide,  such  as  pyrites;  as  sulphate  of  calcium  or  s exists 
barium ;  and  as  a  sulphuretted  hydrocarbon.  In  a  proximate 
analysis  of  coal  about  one-half  the  sulphur  in  any  pyrites  present 
and  all  the  sulphur  existing  as  a  sulphuretted  hydrocarbon  are 
probably  driven  off  with  the  Volatile  Combustible  Matter.  The  rest 
of  the  sulphur  from  the  pyrites  is  oxidized  and  driven  off  during 
the  burning  of  the  Fixed  Carbon  (sulphate  of  iron  being  easily 
decomposed  at  a  bright  red  heat)  unless  the  sulphuric  acid 
formed  is  taken  up  by  an  alkali  or  alkaline  earth. 

The  nearest  approach  we  can  make  to  a  determination  of  the  Determina- 
tion of  the 

conditions  in  which  the  sulphur  exists  in  any  coal  is  to  make  a  conditions, 
determination  of  the  total  sulphur  by  fusion,  and  a  determination 
of  the  sulphuric  acid  in  the  ash.  By  subtracting  the  S  found  by 
the  latter  determination  from  the  total  S  the  difference  may  be 
taken  to  represent  the  amount  existing  as  S  (in  the  form  of  sul- 
phide), and  the  amount  found  in  the  ash  as  that  existing  as  SO3 
(in  the  form  of  sulphate).  These  results  will  be  correct  if  the 
coal  contains  no  carbonates  of  the  alkalies  or  alkaline  earths. 


DETERMINATION    OF   PHOSPHORIC   ACID. 

Burn  off  10  grammes  of  the  coal  or  coke  in  a  crucible,  or,   Burning  off 

.  ....  ,.  .  ,  the  coal 

as  in  anthracite  coal  or  coke  this  is  a  very  tedious  operation,  burn  orcoke. 
it  off  in  a  large  platinum  boat  in  a  tube  in  a  current  of  oxygen. 
A  boat  4  inches  (102  mm.)  long,  and  wide  enough  to  fit  in  a  tube 
^  of  an  inch  (19  mm.)  in  diameter,  will  hold  10  grammes  very 
easily,  and  by  its  use  this  amount  of  coke  or  anthracite  coal  may 
be  burned  off  in  a  current  of  oxygen  in  about  one  and  a  half 
hours.  Treat  the  ash  with  HC1  to  dissolve  any  phosphate  of  cal- 
cium, filter,  and  wash  well  with  water.  Stand  the  filtrate  aside, 
dry,  ignite,  and  fuse  the  insoluble  matter  with  Na-jCO^  Dissolve 


248  THE   CHEMICAL  ANALYSIS   OF  IRON. 

in  water,  filter  from  the  insoluble  matter,  acidulate  the  filtrate  with 
HC1,  and  evaporate  to  dryness.  Redissolve  in  water  and  a  little 
HC1,  filter,  add  this  filtrate  to  the  HC1  filtrate  from  the  first  treat- 
ment of  the  ash,  add  a  little  ferric  chloride  solution  and  a  slight 
excess  of  ammonia.  Acidulate  with  acetic  acid,  heat  to  boiling,  boil 
for  a  few  minutes,  filter,  and  wash  the  precipitate  once  or  twice  with 
boiling  water.  Dissolve  the  precipitate  in  HC1,  evaporate  nearly 
to  dryness,  add  citric  acid,  magnesia  mixture,  and  ammonium, 
and  precipitate  as  directed  on  page  76.  Filter  off,  ignite,  and 
weigh  the  Mg2P2O7  as  there  directed.  Or,  after  dissolving  the 
acetate  precipitate,  as  above,  in  HC1,  evaporate  down,  and  precipi- 
tate the  P2O5  by  molybdate  solution,  as  directed  on  page  81 
et  seq. 


METHODS  FOR  THE  ANALYSIS 

OF 

GASES. 


THE  technical  analysis  of  gases  is  of  growing  importance,  and 
a  knowledge  of  the  methods  of  analysis  and  of  the  manipulation 
involved  is  now  generally  necessary  to  the  iron  chemist.  For  ease 
of  manipulation,  and  for  the  accuracy  of  the  results  obtained  by 
its  use,  Hempel's  form  of  apparatus  is  generally  to  be  preferred. 
It  consists  essentially  of  a  burette  for  holding  and  measuring  the 
gas  B,  Fig.  92  (the  modified  Winkler's  gas-burette),  and  a  pipette, 
G,  Fig.  92,  which  holds  the  reagent.  By  means  of  the  level-tube 
A,  filled  with  water,  the  gas  is  forced  into  the  pipette,  where  it  is 
brought  in  contact  with  the  reagent  and  afterwards  returned  to  the 
burette  and  measured.  By  the  use  of  a  series  of  these  pipettes, 
each  filled  with  a  separate  reagent,  the  various  constituents  of  the 
gas  under  examination  are  absorbed  and  their  volumes  estimated. 

COLLECTING   SAMPLES. 

Fig.  89  shows  a  very  simple  method  for  taking  a  sample  of  gas 
for  analysis.  The  porcelain  tube  A  passes  through  the  brick-work 
into  the  flue  through  which  the  gas  is  carried.  In  the  sketch  a 
portion  of  the  porcelain  tube  is  cut  away,  to  show  the  loose  fila- 
ments of  asbestos  with  which  the  tube  is  filled  to  keep  dust  or 
tarry  matter  from  entering  the  burette.  This  asbestos  must  be  put 
in  very  loosely,  or  else  it  will  pack  and  interfere  with  the  free  pas- 

17  249 


250 


THE   CHEMICAL   ANALYSIS   OF  IRON. 


sage  of  the  gas.  Where  the  gas,  as  from  a  producer,  etc.,  is 
constantly  examined,  it  is  very  convenient  to  have  a  valve  fitted 
permanently  to  an  iron  pipe  screwed  or  cemented  into  the  flue, 
into  which  the  porcelain  tube  may  be  fastened  by  means  of  a 
rubber  or  asbestos*  stopper.  A  glass  tube  of  about  ^  inch 
(6  mm.)  diameter  is  fitted  into  the  outer  end  of  the  porcelain  tube 


FIG.  89. 


Taking  the 
sample 
in  the 
burette. 


A,  Fig.  89,  by  means  of  a  rubber  or  asbestos  stopper,  and  this 
glass  tube  is  connected  by  means  of  the  rubber  tube  C  with  the 
opening  at  the  lower  end  of  the  burette  d.  If  the  gas  is  under 
pressure  (as  is  rarely  the  case),  it  is  only  necessary  to  open  the 
stopcocks  and  allow  it  to  pass  through  the  burette  until  the  air 
is  entirely  displaced.  Usually,  however,  it  is  necessary  to  draw 
the  gas  through ;  and  the  little  india-rubber  pump  D  attached  to 


*  See  page  118. 


ANALYSIS   OF  GASES. 

the  capillary  tube  at  the  upper  end  of  the  burette  is  very  useful  Aspirator 
for  this  purpose.     It  is  fitted  with  a  simple  valve  at  each  end,  so 
that  by  compressing  the  bulb   in  the  hand   its  contents  are  dis- 
charged  through  the  outer  end  while  the  pressure  closes  the  valve     rette' 
at  the  burette  end.    When  the  bulb  is  released  it  resumes  its  shape, 
the  tension  closing  the  outer  valve  and  opening  the  one  towards 
the  burette,  through  which  the  contents  of  the  latter   are  drawn 
into  the  bulb.     A  bulb  of  the   usual   size  will   empty  a    100  c.c. 
burette  in  about  three  strokes.     In  taking  a  sample  of  gas,  turn 
the  3-way  stopcock  b  so  that  the  passage  is  open  through  into  the 
burette,  open  the  stopcock  a  at  the  upper  end  of  the  burette,  and 
pump  the  gas  through  slowly  for  five  or  six  minutes.     Close  the  Compress- 
upper  stopcock  a,  compress  the  rubber  FIQ    Q 


tube  C  between  the  thumb  and  fingers 


rette. 


of  the  left  hand,  and,  holding  the  tube 
with  the  other  hand,  slide  the  left  hand 
towards  the  burette.  This  will  com- 
press the  gas  in  the  burette,  and  by 
closing  the  stopcock  b  while  the  tube 
C  is  thus  held  the  gas  in  the  burette 
will  be  under  pressure.  In  closing  b, 
it  must  be  turned  so  that  the  passage  is  open  from  d  out  through 
C,  as  shown  in  Fig.  90.  Remove  the  burette  to  the  laboratory, 
attach  the  rubber  tube  C  of  the  level-tube  A,  Fig.  92,  to  the  end 
of  the  burette,  loosen  the  pinchcock  E,  and  allow  the  water  to 
run  through  until  it  comes  out  through  the  rubber  tube  on  the 
end  of  the  stopcock.  Close  E,  and  allow  the  burette  and  gas  to 

attain  the  temperature  of  the   laboratory.      Samples   of  gas  for  Other  ves- 
sels for 
analysis  may  also  be  taken  in  glass  tubes  drawn  out  at  the  ends     collecting 

and  closed  by  rubber  tubes  and  pinchcocks  or  pieces  of  glass  rod. 
When  the  sample  is  to  be  taken  to  a  distance,  it  may  often  be  col- 
lected in  a  metal  vessel  with  conical  ends  and  tubes  with  well- 
ground  stopcocks.  Glass  vessels  of  the  proper  shape,  holding 
from  half  a  litre  to  one  litre,  and  fitted  with  glass  stopcocks  and 


252 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


capillary  tubes   made  for  this  purpose,  may  be  purchased  from 

dealers  in  chemical  glass-ware.     From  these  vessels  or  tubes  the 

Transfer-       gas  may  be  transferred  to  the  burette  by  attaching  to  one  outlet  a 

burette.       tube  filled  with  water  and  joined  to  the  burette,  likewise  filled  with 

water,  placing  the  other  end  of  the  vessel  in  water,  lowering  the 

level-tube,  and  drawing  the  gas  into  the  burette. 


Composition 
of  gas. 


Absorbents. 


Method  of 
filling  a 
simple 
pipette. 

Caustic 
potassa 
pipette. 


Method  of 
filling  a 
composite 
pipette. 


REAGENTS    FOR   THE    PIPETTES. 

Blast-furnace  gas,  producer  gas,  and,  in  general,  gases  made 
by  drawing  or  forcing  atmospheric  air  through  coal  or  coke,  con- 
tain varying  amounts  of  carbon  dioxide  (CO2),  oxygen  (O),  carbon 
monoxide  (CO),  hydrogen  (H),  methane,  or  marsh  g'as  (CH4),  and 
nitrogen  (N).  The  best  absorbents  are  caustic  potassa  for  CO2, 
pyrogallol  for  O,  and  cuprous  chloride  in  HC1  for  CO.  Hydro- 
gen is  determined  by  ignition  with  excess  of  oxygen  over  palla- 
dium sponge,  and  marsh  gas  by  ignition  in  a  tube  filled  with 
cupric  oxide.  The  pipettes  required,  therefore,  are  a  simple  pipette 
(G,  Fig.  92)  filled  with  caustic  potassa,  1.27  sp.  gr.,  for  absorbing 
CO2,  which  is  readily  filled  by  placing  in  the  large  tube  of  the 
pipette  a  small  glass  tube,  which  extends  down  to  the  bottom  of 
the  bulb  and  is  connected  outside  with  a  small  glass  funnel  by 
means  of  a  piece  of  gum  tubing.  Pour  the  caustic  potassa  in 
through  the  funnel  until  the  large  bulb  of  the  pipette  and  the  tube 
connecting  the  two  bulbs  are  filled  with  the  liquid.  Draw  the 
liquid  into  the  capillary  tube  until  it  reaches  to  within  a  very  short 
distance  of  the  rubber  tube  on  the  end  of  the  capillary,  and  close 
the  rubber  tube  with  a  piece  of  glass  tubing  or  a  pinchcock,  as 
shown  in  the  sketch  of  the  composite  pipette,  Fig.  91. 

A  composite  pipette  (Fig.  91)  containing  pyrogallol  for  absorb- 
ing oxygen  is  filled  as  follows:  Dissolve  30  grammes  of  pyro- 
gallic  acid  in  75  c.c.  of  water,  attach  a  funnel  to  the  capillary  tube 


253 


FIG.  91. 


ANALYSIS   OF  GASES. 

of  the  pipette  by  a  piece  of  rubber  tubing,  and  fill  it  with  the  solu- 
tion. Attach  a  piece  of  rubber  tubing  to 
the  other  tube  of  the  pipette,  and  by 
gentle  suction  exhaust  the  air ;  this  will 
cause  the  -liquid  to  run  rapidly  through 
the  capillary  tube  into  the  pipette.  Keep 
the  funnel  full  until  the  liquid  which  is 
drawn  through  the  large  bulb  into  the 

second  bulb  fills  the  latter  to  an  inconvenient  extent,  then  stop 
the  suction,  and  very  carefully  blow  the  liquid  back  into  the  large 
bulb.  Fill  the  funnel  again,  and  exhaust  the  air  gently  as 
before.  Repeat  this  until  all  the  solution  of  pyrogallic  acid  has 
been  drawn  in,  and  then  with  the  same  precautions  draw  in  a 
solution  of  caustic  potassa,  1.27  sp.  gr.,  until  the  large  bulb  and 
the  tube  connecting  the  large  bulb  and  the  second  bulb  are  filled 
with  the  liquid,  which  is  now  an  alkaline  solution  of  pyrogallate 
of  potassium.  Close  the  capillary  tube  as  directed  for  the  caustic 
potassa  pipette,  page  252.  Insert  the  small  tube  and  funnel  in  the 
large  tube  of  the  composite  pipette,  as  directed  on  page  252  for 
filling  the  simple  pipette,  and  pour  a  little  water  into  the  last  bulb 
of  the  composite  pipette.  The  amount  of  water  poured  in  should 
not  be  sufficient  to  fill  the  third  bulb,  for  the  pyrogallol  rapidly 
absorbs  the  oxygen  of  the  air  in  the  second  bulb,  and  this  contrac- 
tion causes  the  water  poured  into  the  last  bulb  to  rise  in  the  third 
bulb.  Therefore  the  amount  of  water  should  be  small  enough  to 
permit  small  bubbles  of  air  to  pass  through  to  supply  the  contrac- 
tion in  the  second  bulb,  and  large  enough  to  avoid  emptying  the 
third  bulb  when  the  gas  during  an  analysis  is  forced  through  the 
capillary  into  the  large  bulb  of  the  pipette.  The  amount  of  pyro- 
gallate of  potassium  from  30  grammes  of  pyrogallic  acid  is  suffi- 
cient to  absorb  nearly  1500  c.c.  of  pure  oxygen,  so  that  a  com-  Absorbing 
posite  pipette  filled  in  this  way,  and  securely  sealed  by  the  water 
in  the  third  and  fourth  bulbs,  will  last  for  almost  an  indefinite 
number  of  analyses. 


254 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


Cuprous 
chloride 
pipette. 

Marking 
pipettes. 


Absorption 
of  CO  by 
cuprous 
chloride 
never 
perfect. 


Bromine 
pipette  for 
C2H4. 


Another  composite  pipette  for  absorbing  carbon  monoxide  is 
filled,  as  above  described,  with  a  saturated  solution  of  cuprous 
chloride  in  HC1,  i.i  sp.  gr.,  and  sealed  with  water.  Each  pipette 
should  be  distinctly  labelled  with  the  name  of  the  reagent,  so 
that  no  mistake  can  be  made  in  using  them. 

It  is  worthy  of  note  that  the  absorption  of  CO  by  cuprous 
chloride  is  purely  mechanical,  and  is  never  absolutely  perfect,  so 
that  a  small  amount  of  CO  invariably  remains  in  the  gas  after 
treatment  in  the  cuprous  chloride  pipette.  Moreover,  whenever 
a  gas  absolutely  free  from  CO  is  treated  in  a  cuprous  chloride 
pipette  (which  has  been  previously  used  to  absorb  CO)  and  re- 
turned to  the  burette,  it  will  be  found  to  have  increased  in  volume, 
and  subsequent  combustion  in  a  palladium  tube  will  yield  an 
amount  of  CO2  corresponding  to  this  increase  counted  as  CO. 
If  this  fact  is  overlooked,  the  CO  left  in  the  gas  will  be  counted  as 
methane  if  a  determination  of  this  gas  is  made  in  the  usual  course 
of  the  analysis. 

A  composite  pipette  filled  with  bromine-water  to  absorb 
ethylene  (C2H4)  is  sometimes  used,  as  this  gas  has  been  found 
in  the  gases  from  blast-furnaces  and  producers  using  bituminous 
coal.  But  the  amount  of  ethylene  is  very  small,  and  a  separate 
determination  is  rarely  made,  any  small  amount  being  absorbed 
and  determined  as  CO. 


ANALYSIS   OF   THE    SAMPLE. 

The  burette  containing  the  gas,  with  the  level-tube  filled  with 
water  attached,  as  mentioned  on  page  251,  having  attained  the 
temperature  of  the  laboratory,  raise  the  level-tube  and  open  the 
3-way  stopcock  so  that  the  passage  is  open  for  the  water  to  enter 
the  burette.  If  the  gas  is  shown  to  be  under  a  slight  pressure,  by 
raising  or  lowering  the  burette  bring  the  water  just  to  the  stop- 
cock (if  the  burette  is  graduated  to  read  100  c.c.  from  stopcock  to 
stopcock,  otherwise  bring  the  water  to  the  o  mark),  and  close  the 


ANALYSIS  OF  GASES, 


255 


FIG.  92. 


Method  of 
connect- 
ing the 
burette 
and  the 
pipette. 


stopcock.     Then  open  the  upper  stopcock  for  an  instant  to  allow 
the  gas  to  assume  the  pressure  of  the  atmosphere.     Now  open  the 
3 -way  stopcock  to  allow  the  water  to  enter  the  burette,  hold  the 
level-tube  so  that  the  water  in  the  tube  and  that  in  the  burette  are  Reading  the 
at  the  same  level,  and  observe  the  reading  of  the  burette.     It  is  a     gas  in  the 
very  simple  matter  in  this  way  to  get  exactly  100  c.c.  of  gas,  which 
very  materially  simplifies  the  calculations.     Connect  the  burette 
with  the  pipette  containing  caustic  potassa  by  means  of  the  capil- 
lary connecting-tube,  as  shown  in 
Fig.  92.    Some  little  skill  is  neces- 
sary in  making  this  connection ; 
the  best  way  to  arrange  it  is  as 
follows :    Attach  one  end  of  the 
capillary  connecting-tube  to  the 
top  of  the  burette  by  a  piece  of 
gum  tubing,  wiring  it  if  neces- 
sary, then  compress  between  the 
thumb    and    forefinger    of    one 
hand    the    rubber    tube    on    the 
capillary   of  the   pipette   for   its 
entire   length   above   the   pinch- 
cock  (as  shown  in  Fig.  91),  then 
carefully   introduce    the    end    of 
the      capillary      connecting-tube 
into  the  end  of  the  rubber  tube, 
and  release  the  rubber  tube.     If 
this  is  carefully  done,  the  walls 
of  the  rubber  tube  between  the 
pinchcock   and   the  end   of  the    z>( 
capillary  will  remain  in  contact, 
showing   that   no    air   has   been 
admitted.     Force  the  end  of  the 
capillary  tube  down  to  the  pinch- 
cock,  and  open  the  latter,  allowing  it  to  remain  over  the  capil- 


256  THE    CHEMICAL  ANALYSIS   OF  IRON. 

lary,  as  shown  in  Fig.  93.  The  apparatus  will  now  be  in  the 
position  shown  in  Fig.  92.  Open  the  upper  stopcock  of  the 
burette,  and  then  turn  the  3-way  stopcock  D  carefully  to  admit 
the  water  from  the  level-tube  into  the  burette.  As  the  water 
enters  the  burette  the  gas  is  forced  over  into  the  pipette  G. 
Allow  the  water  to  fill  completely  the  burette  B  and  to  enter  the 
capillary  tube  F  and  fill  it  as  far  as  the  rubber  connection  between 
Determina-  ft  ancj  ^Q  capillary  tube  of  the  pipette  G.  Close  the  upper  stop- 

tion  of 

co2.  cock  of  the  burette,  place  the  pinchcock  on  the  rubber  tube  be- 
tween the  capillary  connecting-tube  and  the  pipette,  and  remove 
the  capillary  connecting-tube  F  from  the  rubber  tube  of  the 
pipette,  leaving  it  attached  to  the  burette.  Take  the  pipette  from 
the  stand  and  shake  it,  to  promote  the  absorption  of  the  CO2, 
which  will  require  only  a  minute  or  two.  Replace  the  pipette, 
attach  the  capillary  connecting-tube  F  as  before,  remove  the 
pinchcock,  place  the  level-tube  A  on  the  floor,  open  the  upper 
stopcock  of  the  burette,  and  allow  the  water  to  run  from  the 
burette  B  into  the  level-tube  A,  drawing  the  gas  from  the  pipette 
G  into  the  burette  B.  When  the  caustic  potassa  solution  has  run 
back  so  as  to  fill  the  large  bulb  and  the  capillary  of  the  pipette 
almost  to  the  rubber  connection,  close  the  upper  stopcock  of  the 
burette  B  quickly,  replace  the  pinchcock  on  the  rubber  tube  of  the 
pipette  G,  detach  the  capillary  connecting-tube  F  from  the  pipette, 
hold  the  level-tube  A  and  the  burette  B  together  to  get  the  water 
on  an  exact  level,  and  take  the  reading  of  the  burette.  The  differ- 
ence between  this  reading  and  the  original  reading  will  be  the 
number  of  c.c.  of  CO2  absorbed;  and  if  the  original  reading  was 
100  c.c.,  each  c.c.  absorbed  will  be  one  per  cent,  of  CO2  in  the 
gas.  If  any  other  volume  of  gas  was  originally  used,  divide  the 
number  of  c.c.  absorbed  by  the  number  originally  used,  multiply 
this  by  100,  and  the  result  is  the  percentage  of  CO2  in  the  gas. 
Determina-  jf  ethylene  is  to  be  determined,  pass  the  gas  into  the  bromine- 

tion  of  J 

water  pipette,  back  into  the  burette,  then  into  the  caustic  potassa 


ANALYSIS   OF  GASES. 


257 


pipette  to  absorb  any  bromine  fumes,  finally  back  into  the  burette, 
and  take  the  reading  as  before.  The  contraction  is  ethylene, 

Now  pass  the  gas  into  the  pyrogallol  pipette,  shake  the  latter 
gently  for  four  or  five  minutes  to  promote  the  absorption  of  the 
oxygen,  return  the  gas  to  the  burette,  and  note  the  reading.  The 
contraction  from  the  last  reading  is  O. 

Pass  the  gas  in  the  same  manner  into  the  cuprous  chloride 
pipette,  detach  and  shake  the  latter  gently  at  short  intervals  for 
five  or  six  minutes  to  promote  the  absorption  of  the  CO,  return 
the  gas  to  the  burette,  and  take  the  reading.  The  contraction 
from  the  last  reading  is  the  CO  absorbed  by  cuprous  chloride. 
To  determine  the  remaining  CO  and  the  H,  the  gas  is  mixed  with 
oxygen  and  burned  over  spongy  palladium.  Fig.  93  shows  the 
arrangement  of  the  apparatus.  A  is  the  palladium  tube,  B  the 
burette,  C  a  pipette  filled  with  water,  D  a  small  gas-burner  for 
heating  the  palladium  tube,  and  E  the  gas-pipe  attached  to  the 
wood-work  of  the  pipette  and  connected  by  a  rubber  tube  with 
a  supply  of  gas.  Instead  of  a  gas-burner  for  heating  the  palla- 
dium tube  a  small  brass  spirit-lamp  may  be  used,  which  is  fastened 
to  the  pipette-stand  by  a  clamp  in  such 
a  position  as  to  bring  the  flame  under 
the  palladium  tube.  With  any  ordinary 
furnace  or  producer  gas  which  con- 
tains 50  per  cent,  and  upwards  of  nitro- 
gen, the  best  plan  is  to  attach  an  oxy-  B 
gen-cylinder  to  the  top  of  the  burette, 
using  a  capillary  tube  and  rubber  con- 
nections', and  fill  the  latter  with  oxygen 

gas.  With  water-gas,  or  when  a  supply  of  oxygen  is  not  available, 
it  is  necessary  to  transfer  a  portion  of  the  unabsorbed  gas  in  the 
burette  to  another  burette,  and  then  to  admit  air  to  the  first  burette 
until  it  is  nearly  filled.  Of  course  it  makes  the  calculation  a  little 
more  complicated  to  change  the  volume  of  the  gas  in  this  way 
during  the  progress  of  an  analysis,  but  in  the  case  of  nearly  pure 


Determina- 
tion of  O. 


Determina- 
tion of 
CO. 


Determina- 
tion of  H. 

Description 
of  the 
apparatus. 


FIG.  93. 


=E 


Transfer- 
ring a 
portion 
of  the 
unab- 
sorbed 
gas. 


THE    CHEMICAL   ANALYSIS   OF  IRON. 

water-gas  the  use  of  oxygen  alone  would  probably  lead  to  an  explo- 
sion, while  with  other  gases,  in  the  absence  of  a  supply  of  oxygen, 
simply  filling  the  burette  with  air  without  letting  out  any  of  the 
gas  might  not  admit  enough  oxygen  to  burn  the  hydrogen.  After 
transferring  a  portion  of  the  unabsorbed  gas,  read  the  burette  care- 
fully to  get  the  volume  of  gas  taken  for  combustion,  and  then 
Calculating  Divide  the  volume  of  gas  taken  for  combustion  by  the  total  volume 

the  volume 

of  gas  unabsorbed,  and  multiply  by  the  amount  originally  taken  for  analysis ; 
the  result  is  the  number  of  c.c.  of  the  original  gas,  to  which  the 
amount  taken  for  combustion  corresponds. 

After  admitting  air  to  the  burette,  which  is  done  by  standing 
the  level-tube  on  the  floor  while  the  burette  is  on  the  table, 
opening  the  3-way  stopcock  so  that  the  water  may  run  into  the 
level-tube,  and  opening  the  upper  stopcock  of  the  burette  until  the 
proper  amount  of  air  has  been  drawn  in,  take  the  reading  of  the 
burette  with  care.  Connect  the  apparatus  as  shown  in  Fig.  93, 
light  the  gas-jet  D,  open  the  upper  stopcock  of  the  burette  B, 
and  by  opening  very  carefully  the  3~way  stopcock  of  the  burette 
cause  the  gas  to  pass  very  slowly  into  the  pipette  C.  The  palla- 
dium tube  should  not  be  heated  to  redness,  but  to  a  temperature 
Precautions  just  below  3.  dark-red  heat.  It  is  very  necessary  to  avoid  carrying 
to  avoid  over  any  water  into  the  hot  palladium  tube,  as  it  would  be  certain  to 
thTpai?  crack  it,  and  for  this  reason  it  is  well  to  see  that  the  capillary  tube 
tubeUr  above  the  stopcock  of  the  burette  and  both  capillary  ends  of  the 
palladium  tube  are  dry  before  making  the  connections.  Any  little 
moisture  may  be  removed  by  means  of  a  very  fine  wire  wrapped 
with  thread.  As  the  water  from  the  combustion  of  the  H  in  the 
palladium  is  liable  to  condense  in  the  end  of  the  tube  near  the 
pipette,  it  is  always  well  to  warm  this  gently  with  the  flame  of 
a  small  spirit-lamp  or  a  piece  of  glowing  charcoal,  so  as  to  drive 
all  the  moisture  into  the  pipette,  and  thus  prevent  its  being  carried 
into  the  hot  part  of  the  palladium  tube  when  the  gas  is  returned 
into  the  burette.  When  the  water  has  risen  in  the  burette  just 
above  the  upper  stopcock,  lower  the  level-tube  and  draw  the  gas 


ANALYSIS   OF  GASES.  359 

back  very  slowly  into  the  burette.  When  the  water  in  the  pipette 
has  risen  to  the  usual  position  in  the  capillary,  replace  the  pinch- 
cock  on  the  rubber  connection  between  the  palladium  tube  and 
the  capillary  tube  of  the  pipette,  extinguish  the  light  under  the 
palladium  •  tube,  and,  when  the  latter  is  cold,  close  the  upper  stop- 
cock of  the  burette,  detach  the  apparatus,  open  the  3-way  stop- 
cock fully,  and  take  the  reading  of  the  burette. 

Now,  if  there  were  no  CO  present  in  the  gas  before  the  com- 
bustion, the  contraction  would  be  due  to  the  condensation  of  the 
H2O  formed  by  the  combustion  of  the  H,  and,  as  2  volumes  of  H 
unite  with  I  volume  of  O  to  form  H2O,  |-  of  the  contraction  would 
be  H.     In  the  presence  of  CO,  however,  there  is  an  additional  con- 
traction beyond  that  caused  by  the  formation  of  H2O,  due  to  the 
fact  that  2  volumes  of  CO  uniting  with   I  volume  of  O  form  2 
volumes  of  CO2.     By  absorbing  the  CO2  in  the  caustic  potassa 
pipette,  and  then  reading  the  burette,  the  second  contraction  is  the 
volume  of  the  CO2,  which  is  the  volume  of  the  CO.    The  first  con-  calculating 
traction,  then,  is  f  of  the  H  -J-  \  the  CO,  and  the  second  contrac-     co 
tion  being  the  volume  of  the  CO,  it  may  be  stated  thus : 
first  contraction =fH  +  -|-  second  contraction, 
or  f  H = first  contraction — \  second  contraction ; 

multiplying  by  -J, 

H=f  first  contraction — \  second  contraction. 
Divide  the  number  of  c.c.  of  H  and  CO  respectively  as  found 
above  by  the  number  of  c.c.  of  the  original  gas  to  which  the 
amount  taken  for  combustion  is  equivalent,  multiply  by  100,  and 
the  result  is  the  percentage  of  H  and  CO.  This  percentage  of  CO 
is  to  be  added  to  the  percentage  found  by  absorption  in  cuprous 
chloride,  and  the  result  is  the  total  CO. 

There  remain  now  in  the  burette  only  nitrogen  and  methane.  Determina- 
tion of 
The  latter  can  be  properly  burned  only  at  a  red  heat  in  contact     CH4. 

with  oxide  of  copper,  forming  H2O  and  CO2.  By  absorbing  the 
CO2  in  a  solution  of  caustic  baryta,  standardized  by  a  normal  solu- 
tion of  oxalic  acid,  and  then  titrating  the  caustic  baryta,  the  volume 


26o 


THE   CHEMICAL  ANALYSIS   OF  IRON. 


Prepara- 
tion of 
standard 
solution 
of  oxalic 
acid  and 
caustic 
baryta. 


of  CH4  is  at  once  indicated.  As  the  normal  solution  of  oxalic  acid 
indicates  the  volume  of  CH4  at  760  mm.  of  barometric  pressure 
and  o°  C.  of  temperature,  the  thermometer  and  barometer  must  be 
noted,  and  the  correction  made  according  to  the  table  (Table  V.). 

Dissolve  5.6314  grammes  of  crystallized  oxalic  acid  in  I  litre 
of  water.  I  c.c.  of  this  solution  indicates  I  c.c.  CO2,  or  I  c.c. 
CH4,  at  760  mm.  barometric  pressure  and  o°  C.  Dissolve  14.0835 
grammes  of  crystallized  hydrate  of  barium  in  I  litre  of  water. 
I  c.c.  of  this  solution  is  equal  to  about  I  c.c.  of  the  oxalic  acid 
solution. 

The  apparatus  for  the  determination  is  shown  in  Fig.  94.  It 
consists  of  a  porcelain  tube,  EE,  in  the  combustion-furnace  F ;  the 

FIG.  94. 


porcelain  tube  is  nearly  filled  with  coarse  oxide  of  copper  between 
loose  plugs  of  asbestos,  or  with  a  roll  of  oxidized  copper  wire  (see 
page  1 1 6).  The  forward  end  is  connected  with  two  absorption- 
bottles,  G,  G,  containing  caustic  baryta  solution.  These  bottles  are 
of  such  a  size  that  25  c.c.  will  fill  them,  so  that  the  gas  in  bubbling 


ANALYSIS   OF  GASES.  26l 

through  forces  a  little  of  the  solution  up  into  the  bulb-tube,  thus 
prolonging  the  contact.  If  they  are  a  little  too  large,  the  solu- 
tion of  caustic  baryta  may  be  diluted,  after  it  is  measured  in  from 
the  pipette,  with  a  little  distilled  water  to  bring  it  to  the  proper 
volume.  -A  is  a  cylinder  containing  oxygen  under  pressure,  or,  Description 
if  this  is  not  available,  a  couple  of  bottles  for  forcing  air  through  paratus.^ 
the  apparatus  may  be  substituted  (such  as  those  shown  in  Fig. 
51,  page  112).  The  cylinder  and  the  burette  B  ar,e  connected,  as 
shown  in  the  sketch  (Fig.  94),  by  means  of  capillary  tubes  with  the 
bottle  C,  containing  caustic  potassa,  1.27  sp.  gr.  The  bottle  C  is 
connected  with  the  bottle  D,  containing  H2SO4,  and  from  D  a 
capillary  tube  passes  to  the  rubber  stopper  in  the  end  of  the  por- 
celain tube  EE.  Start  a  current  of  oxygen  or  air  through  the  Description 
apparatus  (before  attaching  the  absorption-bottles  G,  G),  light  the  process, 
burners  of  the  furnace,  and  raise  the  temperature  gradually  until 
the  tube  is  red-hot.  Continue  the  passage  of  the  oxygen  until  a 
bottle  containing  a  solution  of  caustic  baryta  attached  to  the  end 
of  the  tube  shows  that  no  CO2  is  given  off.  Measure  out  25  c.c. 
of  the  caustic  baryta  solution  into  each  of  the  bottles  G,  G,  and 
attach  them  as  shown  in  Fig.  94,  open  the  upper  stopcock  of  the 
burette  B,  and  by  means  of  the  3-way  stopcock  let  water  into  the 
burette  from  the  level-tube,  so  that  the  gas  from  the  burette  is 
made  to  bubble  very  slowly  into  the  bottle  C.  About  three  or 
four  bubbles  should  pass  into  C  from  the  oxygen  cylinder  to  one 
from  the  burette.  When  the  water  completely  fills  the  burette 
and  the  capillary  tube  in  C,  close  the  upper  stopcock  of  the 
burette,  and  continue  the  passage  of  the  oxygen  from  A  until  it 
is  certain  that  all  the  gas  has  been  carried  through  the  porcelain 
tube  and  the  absorption-bottles.  In  the  mean  time  measure  out 
25  or  50  c.c.  of  the  caustic  baryta  solution  into  a  porcelain  dish, 
dilute  with  water,  add  a  drop  of  phenolphtalein  solution  (made  by 
dissolving  phenolphtalein  in  alcohol),  and  from  a  burette  run  in 
the  standard  solution  of  oxalic  acid  until  the  pink  color  of  the 
solution  just  vanishes.  This  will  give  the  value  of  the  caustic 


262 


THE    CHEMICAL   ANALYSIS  OF  IRON. 


Calculation 
of  the 
result. 


tion  of  N. 


baryta  solution  in  the  normal  oxalic  acid  solution.  When  the 
combustion  is  finished,  detach  the  absorption-bottles,  wash  their 
contents  into  the  dish,  add  a  drop  of  phenolphtalein  solution,  and 
titrate  with  the  oxalic  acid  solution.  The  difference  between  the 
value  of  50  c.c.  baryta  solution  and  the  value  of  the  50  c.c.  from 
the  absorption-bottles,  in  terms  of  the  oxalic  acid  solution,  is  the 
number  of  c.c.  of  CH4  in  the  gas  burned  at  760  mm.  barometric 
pressure  and  o°  C.  Divide  this  by  the  number  of  c.c.  burned, 
reduced  to  760  mm.  pressure  and  o°  C.,  multiply  by  100,  and  the 
result  is  the  volume  per  cent,  of  CH4.  Add  together  the  percent- 
ages obtained  of  CO2  (ethylene,  C2H4),  O,  CO,  H,  and  CH4,  sub- 
tract  the  sum  from  ioo,  and  the  remainder  is  the  percentage  of  N 
by  difference. 


EXAMPLE    OF   ANALYSIS. 
Siemens'  Producer  Gas. 

Volume  of  gas  employed,  99.  j  c.c. 

KHO  pipette 93.5  c.c.        Contraction,    6.2  c.c.  CO2  =     6.21  % 

Pyrogallol  pipette    ....    93.3     "  "  0.2    "  O  =      0.20" 

CuCl  "        ....    74.0     "  "  19.3   «    =  19.36  %  CO 

Transferred  a  portion.                          From  palladium  combustion  1.42"   CO  (total)  =  20.78" 

Remaining  in  pipette   .    .    .    46.8     "  H                =  11.23" 

F46.8  "I 

=  of  original  gas  to  .    .    .      63.24            L~74~X"'7J  CH*            ~  3-x4  " 

Admitted  air  to 98.4     "  K  =    58.44  •• 

IOO.OO  " 

Burned  over  palladium    .    .    87.3     " 

First  contraction n.i     " 

KHO  pipette 86.4     " 

to.o  1 

6         X  ioo    =  1.42  %  CO. 

H  =  %  [ii. i]  -  y3  [0.9] I  =  7.1  c.c.  [^  X  ioo]  =  11.23  %  H. 

Burned  residue  over  oxide  of  copper  and  absorbed  CO2  in  caustic  baryta  solution. 

Thermometer  17°  C.  Barometer  745  mm.  745-° —  I4»4=  73°-6 

7  .0086702  X  ioo     =  .86702 
3  .0037158  X    10    —.037158 
o  x      i     =  .000000 

6  .0074316  X      o.i  —  .00074316 
.90492116 
63.24  c.c.  X  .90492116  =  57.23  c.c.  at  760  mm.  and  o°  C. 

50  c.c.  caustic  baryta  solution  =  48.3  c.c.  oxalic  acid 
After  combustion  50  c.c.        "  "  "       —  46.5  "         "        " 

Therefore  CH4  in  gas  burned  =    1.8  " 

and  -j^  X  100  =  3.14  %  CH4. 

263 


264 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


TABLE    I. 


Atomic  Weights  of  the  Elements  used  in  this  Volume. 


Name. 

Symbol. 

At.  Wt. 

Name. 

Symbol. 

At.  Wt. 

Aluminium 

Al. 

27.  CO 

Manganese     

Mn. 

55.00 

Antimony 

Sb. 

1  22.OO 

Nickel     

Ni.  • 

50.00 

Arsenic  ...        

As. 

7S.OO 

Nitrogen     

N. 

14.00 

Ba 

I  "?7  OO 

Oxygen 

O. 

16.00 

Bromine 

Br. 

So.OO 

Phosphorus     

P. 

31.00 

Ca. 

4O.OO 

Platinum     

Pt. 

197.18 

Carbon                    

C. 

I2.OO 

Potassium   

K. 

39.13 

Cl 

or    CO 

Silicon 

Si 

2800 

Chromium 

Cr 

<?2  13 

1  Sodium   ...        

Na. 

23.00 

Cobalt                     

Co. 

sq.oo 

Sulphur  

S. 

32.00 

Cu 

6  1  4.O 

Tin 

Sn. 

1  18.00 

Hydrogen  

H. 

I.OO 

Titanium     

Ti. 

50.00 

Iodine             

I. 

126.85 

Tungsten    

W. 

184.00 

Iron                         

Fe. 

;6.oo 

Vanadium  

V. 

51  25 

Lead 

Pb 

2O7  OO 

Zinc 

Zn. 

6^.06 

Mg. 

24  OO 

i 

TABLES. 


265 


TABLE    II. 

Table  of  Factors. 


Found. 

Sought. 

Factor. 

Logarithm. 

ALO,  . 

Al  -."'  .    .    .    . 

."mq8 

Q.727<;2?O-IO 

Sb9O,  . 

Sb  ....... 

.7Q22I 

Q.8Q884O7—IO 

SbS3   

Sb  

.7176^ 

O  8'»i;QI27—  IO 

Ma,(NH^«AsnOo  -1-  H,O    . 

As  .    . 

.3Q4.74 

Q  "%o6'?II  I—  IO 

Me  As  O, 

As 

4.8l87 

Q  6847287    IO 

As0Sa  . 

As  

.60076 

o.78i;i?8q-io. 

As  

FeAs2    

I.  77  7  -2 

G.17776^4 

BaSO4        .    . 

s  

.117  14. 

n.I  777070-10. 

SO3 

.•^Ai-jt: 

Q  51^7171—10 

CaSO4    .......... 

CaO  

.41176 

9.6146442—10. 

CaCOo  . 

.77C20 

9.8664587-10. 

CaO                *    . 

CaCO3               

1.787? 

0.2518085 

Cr2O,      .    .'  

Cr  

.68619 

9.8364444-10. 

CoSO4 

Co. 

.38064 

Q.58O5I44-IO. 

CoO  .               

.48^87 

9.6847287-10. 

Co  

CoO  

1.27119 

O.I042I05 

CoO               

Co  

.78667 

9.8957926-10. 

Cu                             ..... 

CuO  

1.21524 

0.097743! 

Cu  S             

1.2524 

0.0977431 

CuO                      

Cu.    

.79849 

9.9022695-10. 

Cu.    .    .   . 

.79849 

9.9022695-10. 

Fe  O 

Fe          *   . 

.70000 

9.8450980-10. 

Fe                                      .    .    . 

FeoO. 

1.38095 

0.1401778 

A  ^3^4      ' 

FeO                   

1.28571 

0.1091429 

pKQO 

Pb                         

.68317 

9.8345288-10. 

PbO                                  .    •    • 

.77507 

9.866860I-IO. 

pbS           

.7888 

9.8969669-10. 

Ma  P  O 

p            

.27928 

9.4460398-10. 

lV1S2r2'^7      

18 


266 


THE   CHEMICAL   ANALYSIS    OF  IRON. 

TABLE    II. — Continued. 


Found. 

Sought. 

Factor. 

Logarithm. 

M^nP,(X 

P0O- 

6^064. 

Q  8o^QA24.    IO 

A  2^0    ' 

MgO. 

.36036 

0.51:67366-10. 

MgCO,  . 

.7^676 

Q.  8780^82-10. 

Mn,O, 

Mn     .    .    . 

.72Ot(2 

Q  8^764.60—10. 

MnO. 

03OI3 

Q  Q68^4.37—IO 

Mn  P  O7 

Mn 

^8712 

9  ^880699   10 

MnO  

.5OOOO 

0.6080700—10. 

MnS 

Mn     ... 

.63218 

9  8008408—10 

MnO 

81609 

o  0117381—10 

K2PtCl6  

KC1  

.3O?S7 

Q.48">I  IO7—  IO. 

K  O 

10308 

928^7373     IO 

NaCl  

Na0O 

.  <t  3060 

9.7247672-10. 

SiO 

Si 

46667 

9  6690099  10 

SnO 

Sn 

78667 

Q  8Q^7Q26    IO 

TKX  . 

Ti  

.60976 

9.78^11580-10. 

V«O-  . 

V           

s6i6 

974.Q4.27I    IO 

WO3 

W 

7Q3I 

9800^270  10 

ZnO 

Zn 

80260 

The  factors  for  Nickel  are  the  same  as  those  for  Cobalt. 


TABLES. 


267 


TABLE    III. 


Percentages  of  P  and  P2O5  for   each  Milligramme  of  Mg2P2O7  when   1O 
Grammes  of  the  Sample  are  used. 


Wt.  of 
Mg2P207. 

P. 

P205- 

Wt.  of 
Mg2P207. 

P. 

P,05. 

Wt.of 
Mg,Ps07. 

P. 

P806. 

Wt   of 
Mg8P20T. 

P. 

PA- 

I 

0.003 

0.006  1 

26 

0.073 

0.166 

51 

0.142 

0.326 

76 

0.212 

0.486 

2 

O.OO5 

0.013 

27 

0-075 

0.173 

52 

0.145 

0.332 

77 

0.215 

0.492 

3 

O.OOS 

0.019 

28 

0.078 

0.179 

53 

0.148 

0.339 

78 

0.218 

0.499 

4 

O.OII 

0.026 

29 

0.081 

0.185 

54 

0.151 

0.345 

79 

O.22I 

0-505 

5 

O.OI4 

0.032 

30 

0.084 

0.192 

55 

0.154 

0.352 

80 

0.223 

0.512 

6 

0.017 

0.038 

31 

0.086 

0.198 

56 

0.156 

0.358  1 

81 

0.226 

0.518 

7 

O.OI9 

0.045 

32 

0.089 

0.204 

57 

o.i59 

0.364 

82 

O.229 

0.524 

8 

O.O22 

0.051 

33 

0.092 

0.2II 

58 

0.162 

0.371 

83 

0.232 

0.531 

9 

0.025 

0.057 

34 

0.095 

0.217 

59 

0.165 

0.377 

84 

0.235 

0-537 

10 

O.O28 

0.064 

35 

0.098 

0.224 

60 

0.167 

0.384 

85 

0.237 

0.544 

ii 

0.031 

0.070 

36 

O.IOI 

0.230 

61 

0.170 

0.390 

86 

0.240 

0.550 

12 

0.033 

0.077 

3f 

0.103 

0.237 

62 

o.i73 

0.396 

87 

0.243 

0.556 

!3 

0.036 

0.083 

38 

0.106 

0.243 

63 

0.176 

0.403 

88 

0.246 

0.563 

14 

0.039 

0.089 

"  39 

0.109 

0.249 

64 

0.179 

0.409 

89 

0.248 

0.569 

15 

O.O42 

0.096 

40 

O.II2 

0.256 

65 

0.181 

0.416 

90 

0.251 

0.576 

16 

0.045 

O.IO2 

4i 

0.114 

0.262 

66 

0.184 

0.422 

9i 

0.254 

0.582 

17 

0.047 

0.108 

42 

0.117 

0.269 

67 

0.187 

0.428 

92 

0.257 

0.588 

18 

0.050 

O.II5 

43 

0.120 

0.275 

68 

0.190 

0.434 

93 

0.259 

o.595 

19 

0.053 

O.I2I 

44 

0.123 

0.281 

69 

0.193 

0.441 

94 

0.262 

0.601 

20 

0.056 

0.128 

45 

O.I26 

0.287 

70 

0.195 

0.448 

95 

0.265 

0.607 

21 

0.059 

0.134 

46 

0.128 

0.294 

71 

0.198 

0.454 

96 

0.268 

0.614 

22 

0.06  1 

O.I4I 

47 

O.I3I 

0.300 

72 

O.2OI 

0.460 

97 

0.271 

0.620 

23 

0.064 

0.147 

48 

0.134 

0.307 

73 

0.204 

0.467 

98 

0.274 

0.627 

24 

0.067 

0.153 

49 

0.137 

0.313 

74 

0.207 

0.473 

99 

0.276 

0.633 

25 

O.O7O 

0.159 

50 

0.139 

0.319 

75 

0.209 

0.479 

100 

0.279 

0.639 

268 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


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TABLES. 


269 


TABLE    V. 

Table  for  Reducing-  Volumes  of  Gases  to  the  Normal  State. 

BY   PROFESSOR   DR.   LEO   LIEBERMANN. 

(From  Winkler's  "Technical  Gas  Analysis.") 

Instructions  for   Use, 

Suppose  the  volume  of  a  gas  to  have  been  found  =  26.2  c.c.  at  742  mm.  barometric  pressure, 
1 8°  C.  temperature,  saturated  with  moisture.  In  order  to  reduce  it  to  the  normal  state  (760  mm., 
o°  C.,  dry),  we  proceed  as  follows: 

1st.  Look  out  the  degree  18  (columns  I  and  4),  and  deduct  the  tension  of  aqueous  vapor  given, 
=  15.3  mm.,  from  the  observed  pressure,  =742.0: 

742.0—15.3  =  726.7  mm. 

2d.  Now  find  the  volume  which  I  vol.  of  the  gas  would  have  at  the  pressure  of  726.7  mm. 
by  looking  out  seriatim  the  figures  7,  2,  6,  and  7  in  column  2  at  the  temperature  18°,  and  placing 
the  numerical  values,  to  be  found  opposite  those  figures,  in  the  same  column,  multiplying  them 
seriatim  by  100,  10,  I,  o.i ;  whereupon  they  are  added  up,  thus: 

7  0.0086408  X  100    =  0.86408 

2  0.0024688  X    10     =0.024688 

6  0.0074064  X      i     =  0.0074064 

7  0.0085408  X      0.1=0.00086408 

0.89703848 

3d.  The  corrected  volume  of  a  cubic  centimetre  is  lastly  multiplied  by  the  number  of  the  c.c. 
previously  found  ;  that  is,  in  the  present  case, 

0.89703848X26.2  =  23.502  c,c. 


Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  o  C. 

0 

I 

O.OOI3I57 

0 

6 

0.0078946 

O 

2 

0.0026315 

0 

7 

0.0092104 

0 

3 

0.0039473 

0 

8 

0.0105262 

0 

A 

0.0052631 

0 

9 

O.OII8420 

O 

5 

0.0065789 

o°  =  4-5 

2/0 


THE    CHEMICAL    ANALYSIS   OF  IRON. 


TABLE  V.— Continued. 


>  i 

Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq.  j 
vapor  in  millim. 
of  mercury 
for  o  C. 

Srer  i,p=. 

mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

I 

I 

0.0013109 

j 

4 

i 

0.0012965 

I 

2 

O.OO262I9 

4 

2 

0.0025930 

I 

--> 
O 

0.0039328 

4 

3 

0.0038895 

I 

4 

0.0052438 

4 

4 

0.0051860 

I 

5 

0.0065548 

i°  =  4-9 

4 

5 

0.0064825 

4°  =  6.0 

I 

6 

0.0078657 

4 

6 

0.0077790 

I 

7 

0.0091767 

4 

7 

0.0090755 

I 

8 

0.0104876 

4 

8 

0.0103720 

1 

9 

0.0117986 

4 

9 

O.OII6685 

2 

i 

0.0013061 

5 

i 

O.OOI29I6 

2 

2 

0.0026123 

5 

2 

0.0025833 

2                     3 

0.0039184 

5 

3 

0.0038750 

2                4 

0.0052246 

5 

4 

0.0051667 

2              5 

0.0065307 

2°  =  5-2 

5 

5 

0.0064584          5°  =  6.5 

2                     6 

0.0078369 

5 

6 

0.0077501 

2 

7 

0.0091430 

5 

7 

0.0090418 

2 

8 

0.0104492 

5 

8 

0.0103335 

2 

9 

0-OH7553 

5 

9 

0.0116252 

3 

i 

O.OOI30I3 

6 

i 

0.0012868 

3 

2 

0.0026026 

6 

2 

0.0025737 

3 

3 

0.0039039 

ii          6 

3 

0.0038606 

3 

4 

0.0052053 

6 

4 

0.0051474 

3 

5 

0.0065066 

3°  -5-6             6 

5 

0.0064343 

6°  =  6.9 

3 

6 

0.0078079 

6 

6 

0.0077212 

3 

7 

0.0091093 

6 

7 

0.0090080 

3 

8 

O.OIO4IO6 

6 

8 

0.0102949 

3 

9 

0.0117119 

6 

9 

0.0145818 

TABLES. 


271 


TABLE  V.— Continued, 


Tempera- 
ture o  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

Tempera- 
ture °  C. 

Pressure 
n  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

7 

I 

0.0012828 

10 

I 

0.0012692 

7 

2 

0.0025656 

10 

2 

0.0025384 

7 

3 

0.0038484 

IO 

3 

0.0038076 

7 

4 

0.0051312 

10 

4 

0.0050768 

7 

5 

0.0064140 

7°  -7-4 

10 

5 

0.0063460 

10°  =  9.  1 

7 

6 

0.0076968 

10 

6 

0.0076152 

7 

7 

0.0089796 

10 

7 

0.0088844 

7 

8 

O.OIO2624 

10 

8 

0.0101536 

X 

7 

9 

O.OII5452 

10 

9 

O.OII4228 

S^. 

£ 

8 

i 

0.0012783 

II 

i 

0.0012648 

%*£ 

8 

2 

0.0025566 

II 

2 

0.0025296 

8 

3 

0.0038349 

II 

3 

0.0037944 

8 

4 

0.0051132 

II 

4 

0.0050592 

8 

5 

0.0063915 

8°  =  8.0 

II 

5 

0.0063240 

11°  =  9-7 

8 

6 

0.0076698 

II 

6 

0.0075888 

8 

7 

0.0089481 

II 

7 

0.0088536 

8 

8 

0.0102264 

II 

8 

O.OIOII84 

8 

9 

0.0115047 

II 

9 

0.0113832 

9 

i 

0.0012737 

12 

i 

0.0012603 

9 

2 

0.0025474 

12 

2 

O.OO252O6 

9 

3 

0.0038211 

12 

3 

0.0037809 

9 

4 

0.0050948 

12 

4 

0.0050412 

9 

5 

0.0063685 

9°  -8.5 

12 

5 

0.0063015 

1  2°=  10.4 

9 

6 

0.0076422 

12 

6 

0.0075618 

9 

7 

0.0089159 

12 

7 

0.0088221 

9 

8 

0.0101896 

12 

8 

0.0100824 

9 

9 

0.0114633 

12 

9 

0.0113427 

2/2 


THE    CHEMICAL   ANALYSIS  OF  IRON. 


TABLE  V.— Continued. 


Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  o  C. 

13 

I 

0.0012559 

16 

I 

0.0012429 

13 

2 

O.OO25II8 

16 

2 

0.0024858 

13 

3 

0.0037677 

16 

3 

0.0037287 

J3 

4 

0.0050236 

16 

4 

0.0049716 

13 

5 

0.0062795 

13°  —  II.  I 

16 

5 

0.0062145 

16°  =13.5 

13 

6 

0.0075354 

16 

6 

0.0074574 

J3 

7 

0.0087913 

16 

7 

0.0087003 

i3 

8 

0.0100472 

16 

8 

0.0099432 

13 

9 

0.0113031 

16 

9 

0.0111861 

H 

i 

0.0012516 

17 

i 

0.0012386 

H 

2 

0.0025032 

17 

2 

0.0024772 

14 

3 

0.0037548 

17 

1 

0.0037158 

14 

4 

0.0050064 

17 

4 

0.0049544 

14 

5 

0.0062580 

14°  =  II.9 

17 

5 

0.0061930 

17°  =  14.4    , 

H 

6 

0.0075096 

17 

6 

0.0074316 

14 

7 

0.0087612 

17 

7 

0.0086702 

H 

8 

0.0100128 

17 

8 

0.0099088 

H 

9 

0.0112644 

17 

9 

0.0111474 

15 

i 

0.0012472 

18 

i 

0.0012344 

15 

2 

0.0024944 

18 

2 

0.0024688 

15 

3 

0.0037416 

18 

3 

0.0037032 

15 

4 

0.0049888 

18 

4 

0.0049376 

15 

5 

0.0062360 

15°  =  I2.7 

18 

5 

0.0061720 

i&°  =  i5«3 

15 

6 

0.0074832 

18 

6 

0.0074064 

i5 

7 

0.0087304 

18 

7 

0.0086408 

15 

8 

0.0099776 

18 

8 

0.0098752 

15 

9 

0.0112248 

18 

9 

0.0111096 

TABLES. 
TABLE  V.— Continued. 


273 


Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  o  C. 

Tempera- 
ture o  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  o  C. 

19 

I 

O.OOI23OI 

22 

I 

O.OOI2I76 

19 

2 

0.0024602 

22 

2 

0.0024352 

19 

3 

0.0036903 

22 

3 

0.0036528 

19 

4 

0.0049204 

22 

4 

0.0048704 

19 

5 

0.0061505 

19°  —  16.3 

22 

5 

0.0060880 

22°  =  19.6 

19 

6 

0.0073806 

22 

6 

0.0073056 

19 

7 

0.0086107 

22 

7 

0.0085232 

19 

8 

0.0098408 

22 

8 

0.0097408 

19 

9 

O.OII0709 

22 

9 

0.0109584 

20 

i 

O.OOI2259 

23 

i 

O.OOI2I35 

20 

2 

0.0024518 

23 

2 

0.0024270  . 

20 

3 

0.0036777 

23 

3 

0.0036405 

20 

4 

0.0049036 

23 

4 

0.0048540 

2O 

5 

0.0061295 

20°  =  1  7.4 

23 

5 

0.0060675 

23°  =  20.9 

20 

6 

0-0073554 

23 

6 

0.0072810 

20 

7 

0.0085813 

23 

7 

0.0084945 

2O 

8 

0.0098122 

23 

8 

0.0097080 

20 

9 

O.OIIO33I 

23 

9 

0.0109215 

21 

i 

O.OOI22I8 

24 

i 

0.0012094 

21 

2 

0.0024436 

24 

2 

0.0024188 

21 

3 

0.0036654 

24 

3 

0.0036282 

21 

4 

0.0048872 

24 

4 

0.0048376 

21 

5 

0.0061090 

21°  =  l8.5 

24 

5 

0.0060470 

24°  =  22.2 

21 

6 

0.0073308 

24 

6 

0.0072564 

21 

7 

0.0085526 

24 

7 

0.0084658 

21 

8 

0.0097744 

24 

8 

0.0096752 

21 

9 

0.0109962 

24 

9 

0.0108846 

2/4 


THE    CHEMICAL   ANALYSIS  OF  IRON. 


TABLE  V.— Continued. 


Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  o  C. 

Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  o  C. 

25 

I 

O.OOI2O54 

28 

, 

0.0011933 

25 

2 

0.0024108 

28 

2 

0.0023866 

25 

3 

0.0036162 

28 

3 

0-0035799 

25 

4 

0.0048216 

28 

4 

0.0047732 

25 

C 

0.0060270 

25°  =  23.5 

28 

5 

0.0059665 

28°  =  28.1 

25 

o 

0.0072324 

28 

6 

0.0071598 

25 

7          0.0x384378 

28 

7 

0.0083531 

25 
25 

Q 

0.0096432 
0.0108486 

28 
28 

8 
9 

0.0095464 
0.0107397 

26 

i 

O.OOI2OI3 

29 

i 

0.0011894 

26 

2. 

0.0024026 

29 

2 

0.0023788 

26 

3 

0.0036039 

29 

3 

0.0035682 

26 

4 

0.0048052 

29 

4 

0.0047576 

26 

5 

0.0060065 

26°  =  25.0 

29 

5 

0.0059470 

29°  =  29.8 

26 

6 

0.0072078 

29 

6 

0.0071364 

26 

7 

0.0084091 

29 

7 

0.0083258 

26 

8 

0.0096104 

29 

8      . 

0.0095152 

26 

9 

O.OI08II7 

29 

9 

0.0107046 

27 

i 

0.0011973 

30 

i 

O.OOII855 

27 

2 

0.0023946 

30 

2 

O.OO237IO 

27 

3 

0.0035919 

30 

3 

0.0035565 

27 

4 

0.0047892 

30 

4 

0.0047420 

27 

5 

0.0059865 

27°  =  26.5 

30 

5 

0.0059275 

30°  =  31.6 

27 

6 

0.0071838 

30 

6 

0.0071130 

27 

7 

0.0083811 

30 

7 

0.0082985 

27 

8 

0.0095784 

3° 

8 

0.0094840 

27 

9 

0.0107757 

30 

9 

0.0106695 

INDEX. 


Absorption   apparatus  for  CO2   in    carbon 

determination 118 

precautions  in  weighing    ....  119 

Acetic  acid,  reagent 33 

Acids  and  halogens 32 

Air-bath 14 

Air-blast  with  Richards'  injector     ....  18 

Alkalies,  determination  of,  in  iron  ores  .    .  216 

and  alkaline  salts 37 

Alkaline  earths,  salts  of 44 

Alumina  and  ferric  oxide,  separation  of     .  209 
separation  of,  by  sulphide  of  am- 
monium    209 

separation  of,  by  caustic  potassa 

or  soda    .    .- 210 

separation  of,  by  hyposulphite  of 

sodium 211 

Aluminium,     separation     of,    from     chro- 
mium   160,  161 

and    chromium,  determination  of,   in 

iron  and  steel 159 

separation  of,  from  P2O5    ....  161 

Ammonia,  reagent 37 

Ammonium,  acetate  of,  reagent 39 

bisulphite  of,  reagent 37 

chloride  of,  reagent 38 

fluoride  of,  reagent 39 

nitrate  of,  reagent 38 

oxalate  of,  reagent 39 

sulphide  of,  reagent 38 

Antimony,  determination  of,  in  iron  and 

steel 166 

arsenic,  copper,  and  lead,  determina- 
tion of,  in  iron  ores 214 


Apparatus 9 

for  the  preparation  of  the  samples  .    .  9 

general  laboratory 13 

Arsenic,  determination  of,  as  As2S3     ...  166 

as  Mg2As2O7 165 

asMg2(NH4)2As208  +  Aq    ...  165 

in  iron  and  steel 164 

by  distillation 165 

by  precipitation 164 

Arsenic  and  antimony,  separation  of  .    .    .  215 
separation  of,  from  copper  and  lead  214 
Arsenic,  antimony,  lead,  and  copper,  deter- 
mination of,  in  iron  ores 214 

Asbestos  stoppers 118 

Balances 29 

Barium,  acetate  of,  reagent 44 

carbonate  of,  reagent 44 

chloride  of,  reagent 44 

hydrate  of,  reagent 45 

iron  ores  containing 193 

Baryta,  caustic,  reagent 45 

caustic,  standard  solution  of,  for  deter- 
mination of  methane 260 

Berthier,  determination  of  carbon  in  iron 

and  steel 108 

Berzelius,  determination  of  carbon  in  iron 

and  steel 107,  108 

determination  of  sulphur  in  iron  and 

steel 55 

Bichromate  of  potassium,  standard  solution 

of,  for  determination  of  iron    .  176 

methods  of  standardizing  180,  182,  183 

proper  strength  of 183 

275 


276 


INDEX. 


Binks,  determination  of  carbon  in  iron  and 

steel 108 

Boat  of  platinum-foil  for  carbon  determina- 
tions in  iron  and  steel 129 

Britton,  permanent  standards  for  color-car- 
bon method 147 

Bromine,  reagent 34 

Bromine-water  for  absorbing  ethylene    .    .  254 
Brunner,  determination  of  carbon  in  iron 

and  steel 107 

Bunsen  burners 16 

chimneys  for 1 6 

Bunsen,  determination  of  MnO2  in  iron  ores  197 
Bunsen's  method  of  rapid  filtration     ...  1 8 
Burette,  best  form  of,  for  volumetric  solu- 
tions       184 

Calcium,  carbonate  of,  reagent 45 

chloride  of,  reagent 45 

Camera,  for  use  in  color-carbon  method     .     146 

Caps  for  reagent  bottles 26 

Carbon  in  carbonaceous  matter,  determina- 
tion of,  in  iron  ores 220 

combined,   determination   of,   in    iron 

and  steel  by  color  method  .  .  141 
limitations  of  color  method  .  .  .  142 
in  white  cast  iron  and  pig-iron  .  149 
Stead's  method  for  low  carbon 

steels 149 

determination  of,  in  iron  and  steel  .    .     106 
determination  of,  in  iron  and  steel  by 
combustion  with  chromate  of  lead 
and  chlorate  of  potassium    ....     109 
determination  of,  in  iron  and  steel  by 
combustion  with  oxide  of  copper  in 

a  current  of  oxygen 112 

determination  of,  in  iron  and  steel  by 
direct  combustion  in  a  current  of 

oxygen 108 

determination  of,  in  iron  and  steel  by 

oxidation  in  air,  solution  of  Fe2O3 

in  HC1  and  combustion  of  residue  .     139 

determination  of,  in  iron  and  steel  by 

solution  and  oxidation  of  the  borings 

by  CrO3  and  H2SO4 113 

determination  of,  in  iron  and  steel  by 
solution  in  chloride  of  copper,  and 
combustion  of  residue 132 


Carbon,  determination  of,  in  iron  and  steel 
by  solution  in  chloride  of  copper 
and  chloride  of  sodium,  and  com- 
bustion of  residue 132 

determination  of,  in  iron  and  steel 
by  solution  in  dilute  HC1  in  an 
electric  current,  and  combustion  of 
residue 138 

determination  of,  in  iron  and  steel  by 
solution  in  double  chloride  of  copper 
and  ammonium,  and  weighing  or 
combustion  of  residue 121 

determination  of,  in  iron  and  steel,  so- 
lution by  fused  chloride  of  silver, 
and  combustion  of  residue  ....  133 

determination  of,  in  iron  and  steel  by 
solution  in  iodine  or  bromine,  and 
combustion  of  residue 132 

determination  of,  in  iron  and  steel  by 
solution  in  sulphate  of  copper,  and 
combustion  of  residue  in  a  current 
of  oxygen 134 

determination  of,  in  iron  and  steel  by 
solution  in  sulphate  of  copper,  and 
combustion  of  residue  by  CrO3  and 
H2S04 135 

determination  of,  in  iron  and  steel 
by  solution  in  sulphate  of  copper, 
and  combustion  of  residue  in. 
vacuo,  volume  of  CO2  being  meas- 
ured  135 

determination  of,  in  iron  and  steel 
by  volatilization  in  a  current  of  Cl, 
and  combustion  of  residue  ....  115 

determination  of,  in  iron  and  steel  by 
volatilization  in  a  current  of  HC1, 
and  combustion  of  residue  ....  121 

monoxide,  absorbent  for 254 

total,    determination  of,  in  iron    and 

steel 107 

Carbonic  acid,  purifying  and  drying  appa- 
ratus for,  in  carbon  determina- 
tions   118 

determination  of,  in  iron  ores  .  .  218 
determination  of,  in  gases  .  .  .  256 
gas,  apparatus  for  generating  .  .  36 

gas,  absorbent  for 252 

Chimneys  for  Bunsen  burners 16 


INDEX. 


277 


Chlorine,  reagent 35 

Chrome  iron  ore,  analysis  of 224 

Chromic  acid,  reagent 35 

Chromium,  indication  of,  in  iron  ores     .    .  224 

determination  of,  in  iron  ores  ....  223 

determination  of,  in  iron  and  steel  .  .  162 
separation  of,  from  aluminium  .  .  160,  161 
volumetric  method  for  determination 

of,  in  iron  and  steel 163 

and   aluminium,  determination  of,  in 

iron  and  steel 159 

Cinder,  mill  and  tap,  analysis  of 239 

Citric  acid,  reagent 34 

Clay,  methods  for  the  analysis  of     ....  232 

Coal,  analysis  of  the  ash  of 244 

and  coke,  methods  for  the  analysis  of  243 

determination  of  sulphur  in 245 

proximate  analysis  of 243 

Cobalt,  determination  of,  as  CoSO4 .    .    .    .  158 
and  nickel,  determination  of,  in  iron 

and  steel 157 

Coke,  determination  of  sulphur  in  ....  245 

Combined  carbon,  determination  of    ...  141 

direct  method 141 

indirect  method 141 

Combined  water,  determination  of,  in  iron 

ores 220 

Comparison -tubes  for  color-carbon  method  145 

Cone,  Gooch's  perforated 21 

Copper,  anhydrous  sulphate  of,  in  pumice, 

reagent 46 

determination  of,  in  iron  and  steel  by 

electrolysis 154 

as  Cu2S 156 

as  CuO 156 

by  precipitation  by  hyposulphite 

of  sodium 156 

metallic,  reagent 46 

oxide  of,  reagent 47 

sulphate  of,  reagent 46 

and    ammonium,  double  chloride  of, 

reagent 47 

lead,  arsenic,  and  antimony,  determi- 
nation of,  in  iron  ores 214 

Counterpoised  niters 21 

Craig,   determination  of  sulphur    in   iron 

and  steel 57 

Crucible,  Gooch's  perforated 20 


Crucibles,  platinum 26 

method  of  cleaning 27 

Crucible-tongs,  forms  of 29 

Cupric  chloride,  reagent 47 

Cuprous    chloride    for    absorbing    carbon 


monoxide 


Desiccators 

Deville,  determination  of  carbon  in  iron 

and  steel 

Dexter's  method  of  separation  for  Cr  and 

Al    .    . 

Dishes,  platinum 

Distilled  water 

apparatus  for  making 

Drill-press 

for  holding  half  pig  of  iron     .... 
Drown,    determination  of  silicon   in  iron 

and  steel 64 

determination  of  sulphur  in  iron  and 

steel 

determination  of  titanium  in  iron    .    . 
Drying  and  purifying  apparatus  for  CO2  in 

carbon  determinations 

Drying  properties,  different,  of  H2SO4  and 
CaCL   , 


254 

26 

160 

28 

31 

12 

,65 

'53 
118 


Eggertz,  determination  of  carbon  in  iron 

and  steel 108 

determination  of  combined  carbon  in 

iron  and  steel 141 

determination  of  phosphorus  in  iron 

and  steel 83 

Elliott,  determination  of  sulphur  in  iron 

and  steel 60 

Emmerton,  determination  of  phosphorus  in 

iron,  steel,  and  iron  ores 85 

Eschka,  determination  of   sulphur  in  coal 

and  coke 246 

Ethylene,  absorbent  for 254 

determination  of,  in  gases 256 

Feather  for  removing  precipitates    ....      25 
Ferric  chloride  solution,  standardizing  so- 
lutions of  permanganate  and  bichromate 

by 180 

Ferrous  oxides,  determination  of,  in  iron 
ores  .  ,     I 86 


2/8 


INDEX. 


Ferrous  sulphate,  reagent 48 

standardizing   solutions    of   per- 
manganate and  bichromate  by  .  183 

Filter-paper 22 

Filter-pumps 17 

Filters,  apparatus  for  washing 23 

ashless 23 

Filtering-tubes   for  carbon  determinations 

in  iron  and  steel 128 

Filtration,  Bunsen's  method  of 18 

Gooch's  method  of 20 

Fire-sand,  methods  for  the  analysis  of  .    .  242 

Flue-cap  for  acid  hoods 15 

Forceps 29 

for  use  in  carbon  determinations  in  iron 

and  steel 125 

Ford,  determination  of  manganese  in  iron 

and  steel 96 

rapid  method  for  determination  of  sili- 
con in  pig-iron 68 

Fresenius,  determination  of  phosphorus  in 

iron  and  steel 72 

determination  of  sulphur  in  iron  and 

steel 56 

Galbraith,   volumetric    method   for   deter- 
mination of  chromium  in  iron  and  steel .  163 
Gas,  Siemens'  producer,  example  of  analy- 
sis of    263 

Gases,  analysis  of,  by  Hempel's  apparatus  254 

collecting  samples  of,  for  analysis    .    .  249 

heating,  composition  of 252 

methods  for  the  analysis  of 249 

reagents 36 

Genth,  method  of  decomposing  chrome  ores.  224 

separation  of  Al  and  Cr 161 

Glass  filtering-tube  for  carbon  determina- 
tions in  iron  and  steel 128 

Gmelin,  O.,  determination  of  carbon  in  iron 

and  steel 107 

Gooch,  separation  of  TiO2  and  A12O3     .    .  195 

Gooch's  method  of  filtration 20 

perforated  crucible  and  cone    ....  20 
Graphitic  carbon,  determination  of,  in  iron 

and  steel 140 

Hempel's    apparatus    for    the    analysis    of 

gases 249 


Hogarth,  specific  gravity  flask 226 

Hydrochloric  acid,  reagent •  .  32 

Hydrofluoric  acid,  apparatus  for  distilling  .  33 

reagent 33 

Hydrogen,  combustion  of,  with  spongy 

palladium 257 

Hydrogen  gas,  apparatus  for  generating  .  36 
Hygroscopic  water,  determination  of,  in 

iron  ores < 173 

Igniting  precipitates 16 

Insoluble  silicious  matter  in  iron  ores,  an- 
alysis of 200 

Iodine,  reagent 34 

Iron  and  ammonium,  double  sulphate  of, 

reagent 48 

in  iron  ores,  titration  by  standard  solu- 
tion of  permanganate  of  potas- 
sium    176 

bichromate  of  potassium   ....  176 

ores,  method  of  sampling 172 

total,  determination  of,  in  iron  ores     .  174 

deoxidation  by  NH4HSO3    ...  178 

deoxidation  by  SnCl2 178 

deoxidation  by  Zn 175 

wire,  reagent 48 

standardizing  solutions  of  perman- 
ganate and  bichromate  by     .    .  182 

Karsten,  determination  of  graphitic  carbon 

in  iron  and  steel 140 

determination  of  sulphur  in  iron  and 

steel 53 

Kudernatsch,  determination  of  carbon  in 

iron  and  steel 107 

Langlcy,  determination  of  carbon  in  iron 

and  steel 108 

Lead,  chromate  of,  reagent 49 

determination  of,  as  PbSO4  in  iron  ores  214 
oxide  of,  dissolved  in  caustic  potassa, 

reagent 50 

peroxide  of,  reagent 50 

copper,  arsenic,  and  antimony,  deter- 
mination of,  in  iron  ores 214 

Limestone,  methods  for  the  analysis  of  .    .  228 

occasional  constituents  of 229 


INDEX. 


279 


Lundin,  determination  of  arsenic  in  iron 

and  steel 165 

Magnesia  mixture,  reagent 51 

Manganese,  determination  of,  as  MnS    .    .  94 

as-Mn2P2O7 93 

as  Mn3O4 •    •    .    .    .  94 

determination  of,  in  iron  and  steel  by 

acetate  method 90 

by  Ford's  method 96 

by  HNO3  and  KC1O3  method  96 

rapid  methods 98 

remarks   on   use   of   acetate 

method 95 

volumetric  method     ....  98 

Volhard's  method 98 

Williams'  method 100 

in    pig-iron,   spiegel,  and   ferro- 

manganese  by  Ford's  method   .  98 
determination  of,  in  spiegel  and  ferro- 
manganese    by    Pattison's 

method 103 

by  Williams'  method     .    .    .  102 

in  steel  by  the  color  method     .    .  104 
in  steels  containing  much  silicon 

by  Ford's  method 97 

methods  for  determination  of,  in  iron 

ores , 196 

separation  of,  from  copper,  nickel,  and 

cobalt 92 

Manganese,  binoxide  of,  in  iron  ores  .    .    .  196 
determination    of,    by    Bunsen's 

method 197 

determination  of,  by  ferrous  sul- 
phate method . 198 

Marguerite's  method  for  determination  of 

iron 176 

McCreath,  determination  of  carbon  in  iron 

and  steel 108 

Measuring-glasses  for  reagents 25 

Mercuric  oxide,  reagent 49 

Mercurous  nitrate,  reagent 49 

Metals  and  metallic  salts,  reagents  ....  46 
Methane,  determination  of,  in  gases   .    .    .  260 
Microcosmic  salt,  quantity  required  in  the 
determination  of  MgO  in  lime- 
stones    229 

reagent 39 


PAGE 

Molybdate  solution,  reagent 51 

Mortar,  agate,  with  Stow  flexible  shaft  .    .  n 

and  pestle,  steel,  for  crushing  ores  .    .  9 

hardened  steel,  for  spiegel 12 

Nickel,  determination  of,  as  Ni2S  or  NiO  .  158 

separation  of,  from  cobalt 157 

and  cobalt,  determination  of,  by  elec- 
trolysis   158,  159 

in  iron  and  steel 157 

separation  of,  from  copper    ...  157 
cobalt,  zinc,  and  manganese,  determi- 
nation of,  in  iron  ores 212 

Nitric  acid,  reagent  . 32 

Oxalate  of  ammonium,  quantity  required  in 

the  determination  of  CaO  in  limestones  .  228 

Oxalic  acid,  reagent 34 

standard  solution  of,  for  determination 

of  methane 260 

Oxide  of  copper  plugs,  preparation  of    .    .  116 

Oxygen  gas,  reagent 37 

absorbent  for 252 

determination  of,  in  gases 257 

Pan,  aluminium,  for  weighing  samples  .    .  30 
Parry,  determination  of  carbon  in  iron  and 

steel 108 

Pattison,  determination   of  manganese   in 

spiegel  and  ferro-manganese 103 

Pearse,  determination  of  carbon  in  iron  and 

steel 108 

Penny's  method  for  determination  of  iron  .  176 
Perforated  boat  and  holder  for  filtering  car- 
bonaceous residues  from  iron  and  steel  122 
Permanent  standards  for  color-carbon  de- 
terminations      147 

Permanganate  of  potassium,  standard  solu- 
tion  of,   for  determination   of 

iron 176 

methods  of  standardizing,  180, 182,  183 

proper  strength  of 183 

Peters,  determination  of  manganese  in  steel 

by  color  method 104 

Phosphoric  acid,  determination  of,  in  coal 

and  coke 247 

in  iron  ores 192 


280 


INDEX. 


Phosphorus,  determination  of,  in  iron  and 
steel,      the      combination 

method 84 

rapid  method 85 

determination  of,  in  iron  and  steel   .  72 

by  the  acetate  method  ...  72 

by  the  molybdate  method  .    .  80 
in  iron,  steel,  and  iron  ores  by 
the  acetate  method,  precautions 

necessary 76 

determination  of,  in  iron,  steel,  and 
iron  ores,  by  molybdate  method,  pre- 
cautions necessary 83 

determination  of,  as  Mg2P2O7  ....  76 
Mg2P2O7,  with  previous  precipita- 
tion as  phospho-molybdate    .    .  82 
determination  of,  as  phospho-molyb- 
date of  ammonium 83 

determination   of,   in  iron  and  steel, 

when  titanium  is  present  .    .    .    .  77,  85 
separation  of,  from  arsenic    ....    74,  83 

Phospho-titanate,  insoluble 151 

Pichard,    determination  of  manganese   in 

steel  by  color  method 104 

Pipette,  Hempel's  simple,  method  of  filling  252 
Hempel's    composite,  method  of    fill- 
ing     252 

Plate,  chilled-iron,  and  inuller 9 

Platinic  chloride  solution,  reagent  ....  50 

Platinum  apparatus 26 

Platinum  combustion-tube  for  carbon  deter- 
minations in  iron  and  steel 125 

Platinum   filtering-tube  for  carbon    deter- 
minations in  iron  and  steel 128 

"  Policemen"  for  removing  precipitates  .    .  25 

Potassa,  caustic,  reagent 41 

Potassa  and  soda,  separation  of 217 

Potassium,  bichromate  of,  reagent   ....  42 

bisulphate  of,  reagent 42 

chlorate  of,  reagent 42 

ferricyanide  of,  reagent 43 

ferrocyanide  of,  reagent 43 

iodide  of,  reagent 43 

nitrate  of,  reagent 41 

nitrite  of,  reagent 41 

permanganate  of,  reagent 43 

sulphide  of,  reagent 41 

Purifying  apparatus  for  oxygen  and  air  .    .  116 


Pyrogallate  of  potassium 253 

absorbent  power  of 253 

Rack  for  permanent  standards  in  color-car- 
bon method 148 

Rapid  evaporations,  apparatus  for   ....  15 

Reagents 31 

for  the  analysis  of  gases 252 

for  determining  phosphorus 51 

Regnault,  determination  of  carbon  in  iron 

and  steel 107 

Richards'  injector 17 

Richter,  determination  of  carbon  in  iron 

and  steel 108 

Riley,   determination   of  titanium    in  pig- 
iron 151 

Rose,  separation  of  alumina  and  ferric  oxide  210 

Rubber  stoppers 26 

Safety-guard  tube  in  CO2  determinations    .  118 

Sampling  iron  ores,  method  of 172 

pig-iron,  method  of 12 

Sand-bath 13 

Schoffer,  determination  of  tungsten  in  iron 

and  steel 169 

Siemens'  producer  gas,  example  of  analysis 

of 263 

Silica,  determination  of,  in  iron  ores  .    199,  208 
alumina,  lime,  magnesia,  oxide  of  man- 
ganese, and  baryta,  determination  of, 

in  iron  ores 199 

Silicon,    determination    of,     in    iron    and 

steel 63 

by  solution  in  HNO3  and  IIC1     .  63 

by  solution  in  HNO3  and  H2SO4.  64 
by  volatilization  in   a   current  of 

chlorine  gas 65 

determination    of,   in    pig-iron,    rapid 

method  by  Ford 68 

Slag,  basic,  analysis  of 240 

refinery,  analysis  of 239 

and  oxides,  determination  of,  in  iron 

and  steel 70 

by  solution  in  iodine 70 

by  volatilization  in  a  current  of 

chlorine  gas 71 

Slags,  methods  for  the  analysis  of   ....  237 

converter,  analysis  of 239 


INDEX. 


28l 


PAGE 

Slags  decomposed  by  HC1,  analysis  of  .    .    237 
not  decomposed  by  HC1,  analysis  of  .    239 
Smith,  J.  L.,  determination  of  alkalies  in 

minerals 217,  234 

Soda,  caustic,  reagent 39 

Soda  and  potassa,  separation  of 217 

Sodium,  acetate  of,  reagent 40 

carbonate  of,  reagent 40 

hyposulphite  of,  reagent 40 

nitrate  of,  reagent 40 

thiosulphate  of,  reagent 40 

and  ammonium,  phosphate  of,  re- 
agent    39 

Sonnenschein,  determination  of  phosphorus 

in  iron  and  steel 80 

Spatulas,  platinum 28 

Specific  gravity  of  iron  ores,  method  of  de- 
termining      226 

Standardizing  volumetric  solutions  for  de- 
termination of  iron 179 

by  solution  of  ferric  chloride    .    .     180 

by  iron  wire 182 

by  ferrous  sulphate 183 

Stead's  chromometer 150 

Stead,  determination  of  combined  carbon 

in  low  carbon  steels  and  irons 149 

Sulphate   of  barium,  determination  of,  in 

iron  ores 191 

Sulphates,  soluble,  determination  of,  in  iron 

ores ~ 191 

Sulphur,  as  sulphides,  in  iron  ores  ....    192 

conditions  of,  in  coal 247 

determination  of,  in  coal  and  coke  .  .  245 
determination  of,  in  iron  and  steel  .  .  53 
determination  of,  in  iron  and  steel  by 

rapid  method 60 

determination  of,  in   iron   and   steel, 

special  precautions  in  pig-iron     .    .       59 
determination  of,  in  iron  and  steel  by 

evolution  as  H2S 53 

determination  of,  in  iron  and  steel 
by  evolution  as  H2S  and  absorption 
in  alkaline  solution  of  nitrate  of 

lead 53 

determination  of,  in  iron  and  steel 
by  evolution  as  H2S  and  absorp- 
tion and  oxidation  by  bromine  and 
HC1 56 


Sulphur,  determination  of,  in  iron  and  steel 
by  evolution  as  H2S  and  absorption 
and  oxidation  by  permanganate  of 

potassium 57 

determination  of,  in  iron  and  steel  by 
evolution  as  H2S  and  absorption  and 

oxidation  by  peroxide  of  hydrogen  .  57 
determination  of,  in  iron  and  steel  by 
evolution  as  H2S  and  absorption  in 
ammoniacal   solution  of  nitrate   of 

silver 55 

determination  of,  in  iron  and  steel  by 

oxidation  and  solution 57 

method  of  reporting  amount  of,  in  coal  246 

total,  determination  of,  in  iron  ores     .  190 
Sulphuretted  hydrogen  gas,  apparatus  for 

generating 36 

Sulphuric  acid,  reagent 32 

Sulphurous  acid,  reagent 35 

Svanberg  and  Struve,  phospho-molybdate 

reaction 80 

Tartaric  acid,  reagent 34 

Tin,  determination  of,  in  iron  and  steel .    .  167 
Titaniferous    iron  ores,   method  of  recog- 
nizing    193 

Titanic  acid,  determination  of,  in  clay    .    .  235 
determination  of,  in  iron  ores  .    .  194 
iron  ores  containing  analysis  of  .  206 
interference  of  P2O5  with  precipi- 
tation of 151 

separation  of,  from  P2O5   ....  152 

tests  for,  in  iron  ores  .    .    .    .  193,  194 

Titanium,  determination  of,  in  iron     ...  151 

by  precipitation 151 

by  volatilization 153 

Triangles  and  tripods  of  platinum  ....  28 

Tripods 17 

Tungsten,  determination  of,  in  iron  ores    .  225 

determination  of,  in  iron  and  steel  .    .  168 

Ullgren,  determination  of  carbon  in  iron 

and  steel      108 

Vanadium,  determination  of,  in  iron  ores  .  225 

determination  of,  in  iron  and  steel  .    .  169 
Volhard,  determination   of  manganese   in 

iron  and  steel 9& 


282 


INDEX. 


PAGE 

Washing-bottles,  forms  of 24 

Watch-glasses,  balanced 30 

Water-bath,   for   determination    of  hygro- 
scopic water  in  iron  ores 173 

for   use  in  color- carbon  method  and 

color-manganese  method 143 

Watts,  determination  of  silicon  in  iron  and 

steel 65 

Weyl,  determination  of  carbon  in  iron  and 
steel  ,     108 


Williams,  determination  of  manganese  in 

iron  and  steel 100 

in  spiegel  and  ferro-manganese    .  102 
Wohler,  determination  of  carbon   in   iron 

and  steel 107 

separation  of  alumina  and  ferric  oxide  211 

Zinc,  determination  of,  in  iron  ore  ....  212 

metallic,  reagent 50 

oxide  of,  in  water,  reagent 51 


THE    END. 


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